The American With Disabilities Act - 1885 Words

Introduction/Brief History As humans, it is our duty to make the world a better, and safer place for all the creatures that live on earth. We may not always do but we try most of the times. Whenever there is a problem or the need to change something that is not convenient, the governments of our countries come up with laws and regulations to solve these problems. Ever since the beginning of times a few children were born with disabilities, it was very hard for them to survive due to lack of resources and accommodations; in some countries they were even killed at birth. Over time the governments realized that there was a problem for children and adults and disabilities that needed to be solved. The American government came up with the ADA also known as the American with Disabilities Act, a civil rights law that prohibits discrimination against disability, it was signed in July of 1990 and effective in January of 1992. It was a great change for disabled people, they were more protected against discrimination, th ey had more rights, and most public facilities, commercial buildings and schools began installing infrastructures that would make that would make accessibility for disabled more efficient. Since then life is much easier for disabled individuals. The ADA Requirements for playgrounds, which is the focus of this paper, discusses the infrastructures and designs that need to be met in playgrounds at schools, parks, homes and other facilities. The ADA requirements forShow MoreRelatedThe Disabilities Of The Americans With Disabilities Act1551 Words   |  7 Pageswith a disability (US Census Bureau, 2015). There are 6.4 million children between the ages of 3 to 21 that are receiving special education services (National Center for Education Statistics, 2014). In Georgia, 23.4% of the population are people under the age of 21 living with a disability (Erickson Schrader, 2014). Bulloch County has a population of 71,214 and of the entire population, 16% of them are living with a disability (Cornell, 2012). By the standards of the Americans with DisabilitiesRead MoreThe Americans With Disabilities Act1277 Words   |  6 Pageshaving a disability was seen as a physical imperfection. People with disabilities were treated as moral and social subordinates. We were trained that if a person had a disability they were not able to perform a task with the same ability as a normal person. They have been denied jobs for which they are highly qualified because they have been considered incompetent, or because employers were not comfortable with their presence in the workplace. Occasionally people with certain disabilities have beenRead MoreThe Americans With Disabilities Act931 Words   |  4 Pageslaw in 1990, the Americans with Disabilities Act (ADA) has been a challenge for employers to implement. This law prohibits discrimination against people with disabilities in both public and public businesses. There were numerous lawsuits where disabled employees have charged that employers h ave failed to accommodate his or her needs in the workplace. However, Supreme Court decisions interpreted the act in a way that made it difficult to prove that an impairment was a disability thereby ruling inRead MoreThe American With Disabilities Act971 Words   |  4 Pages The American with Disabilities Act was signed into law on July 26, 1990, by President George H.W. Bush. (Mayerson, 1992). According to Hallahan, Kauffman, Pullen (2015, P, 14) â€Å"the ADA provides protection of the civil rights in the specific areas of employment, transportation, public, accommodation, State and local government, and telecommunication. According to Mayerson (1992, P1) â€Å"the ADA did not began at the signing ceremony at the White House, but it began in the communities, when parentsRead MoreAmericans with Disabilities Act779 Words   |  3 PagesAmericans With Disabilities Act Website 1 http://www.cato.org Sponsoring Agency: The CATO Institute Content and Website Layout: The CATO Institute has afforded the public with myriad resources, regarding disabilities, education, child policy, welfare, government and politics. This website is fraught with publications, informative videos and commentary. Summary of Contributions: In essence, the CATO Institute has invariably aided the public, including segments of the population who have sufferedRead MoreThe Americans With Disabilities Act Essay964 Words   |  4 Pages All Americans deserve the right to receive the best medical treatment available, that includes those with disabilities. So what is ADA? What makes it so essential? ADA may seem like just a couple letters from the alphabet, although to a person that has a disability it means a whole lot more. ADA stands for Americans with Disabilities Act. The Americans with Disabilities Act is extremely vital in the medical field. Not only is it the law to ensure that there is appropriate access to those with disabilitiesRead MoreThe Americans With Disabilities Act1577 Words   |  7 PagesAmericans with Disabilities Act I Introduction The Americans with Disabilities Act (ADA) is federal legislation designed to prevent discrimination against disabled people. It applies to all disabled persons, no matter the nature of their disability. This paper examines the ADA and discusses some of the ramifications of the legislation. II Americans with Disabilities Act The Americans with Disabilities Act (hereafter ADA) was enacted in 1990, and its purpose is stated thusly: â€Å"The Americans withRead MoreThe On The American With Disability Act931 Words   |  4 PagesAs a supervisor according to my knowledge based on the American with Disability Act, I as supervisor would give Cheryl an oral warning. I will notify her that the ADA law states that she needs to do her job appropriately. I will check on her time and performance. If she did not perform a good job then I will give her a written warning. My first recommendation is that she should meet the EPA advisor and get some assistance from that program because that program may give her the lesson how to improveRead MoreAmericans with Disability Act926 Words   |  4 PagesAmericans with Disabilities Act was established to restrain illegal discrimination in employment against individuals qualified to be disabled. The purpose of the law was to generally end discrimination in the place of work and to deliver equal employment chances for individuals living with disabilities or have had histories of disabilities. The act defends employees that experience physical or mental deficiency that greatly limits a key life activity. In addition to that, it protects the rights ofRead MoreThe American With Disabilities Act998 Words   |  4 PagesDisability is a complex word to define. Several attempts have been made to provide simplistic definition of the word however, it just added to more confusion and misuse of what the word disability m eans. The American with Disabilities Act (ADA) defines disability as â€Å"a physical or mental impairment that limits one or more of the major life activities of such individual†. There are many different perspectives of what the term disability means from an administrative, clinical, or academic research

The Conflict Of God And Empire - 1408 Words

God and Empire is ultimately about the Roman Empire and its relationship with/to the early church. I believe that Crossan’s key idea or â€Å"thesis† is that civilization naturally promotes developing an empire and violence, but the bible, regardless of the many violent acts inside of it, is encouraging use to choose a life of nonviolence. Civilization currently exists on the intrinsic belief that violence is normal, which is a principle that was obviously held in early Rome. In fact, it is this imperialistic ideology and belief in violence that gives the emperor his power. Oddly enough, it makes him seen as both a divinity and a peacemaker. In the society of the Roman Empire, peace built on the value of victory and therefore it comes with the forced acceptance of injustice, because always, in order for one to win, the other must lose. Crossan also explains that although civilization tends to normalize violence, it is possible that violence is not our ultimate destiny. He shows that both possibilities; violence and nonviolence, are present in the bible, often side by side. Crossan would like us to realize that the choice between the violence and none violence is ours to make. He shows that there is proof of this choice in both the Old and New Testament. Moreover, the Bible, he says, â€Å"is about the ambiguity of divine justice† (p. 94). Crossan’s analysis really begins with chapter 2. In this chapter he digs into the debate in The Old Testament surrounding the principles of justiceShow MoreRelatedThe Egyptian, Assyrian, And Persian Empires1580 Words   |  7 PagesFrom 1567 to 330 B.C. humanity experienced many subsequent development as well as decline in its civilizations. Among these events emerged three colossal empires that had shaken the world and forever changed the course of human history. The Egyptian, Assyrian, and Persian Empires have been instrumental in influencing technology, religion, and ideas throughout the world. Various factors have contributed to the success and downfall of these giants. Each of the â€Å"World Powers† have similarities as wellRead MoreHistory And Advances Of The Christian Church Essay1003 Words   |  5 Pagesthe course of Foundations of Reflection: God, my mission is to appreciate and learn the history and advances of the Christian Church. As students, we analyze cultural texts and describe meaningful events to develop an answer to â€Å"who,† â€Å"what,† and â€Å"why† there is a transcendent God. This composition will focus the historical-social context, ecclesial context, and modifications to the Church that occurred from three critical events; Fall of the Roman Empire, World War II, and the Celebration of theRead MoreChristianity And Islam : The World s Largest Religions1501 Words   |  7 Pagesreligions teach that â€Å"there is One true and only God, the righteous and transcendent Creator of all things in heaven and earth† (34). Both religions have foundational texts, Christianity has the bible and Islam has the Quaran. Although among their similarities the two religions differ in many ways. In this essay I will focus on the two religions origins and geographical locations, key people who fostered the religion, who they appealed to and their empires. Much like we all were born on a day we callRead MoreHow Did The Construction Of The Angkor State Lead A Collapse?1040 Words   |  5 Pagesfrom Java, marking the beginning of the Angkor period. With strong political, religious, and economic power, the Khmer empire established a territory including Cambodia, parts of southern Vietnam, and much of Thailand. Angkor, the capitol city of the Khmer empire, came to be a complex and prosperous metropolis that supported a very large population. Eventually, the Khmer Empire came to a cultural demise midway through the fifteenth century. The unifying culture came to an end, and many of the factorsRead MoreThe Economic Activity Of The Early Roman State1616 Words   |  7 Pageswere the power house, and they continually made policy and governed. The Roman Senate also seemed like an advisory council, because of the job and role they played. 5) The flaws in the Roman Republic the Conflict of Orders highlighted was the inequalities found in Roman society, which led to conflict between the elite and the rest of the population in Rome. The elite were called the patricians, while the majority of the population was called the plebeians, and plebeians rebelled against the patriciansRead MoreIslam, The Ottoman And Safavid Empire1528 Words   |  7 PagesIslam, the Ottoman and Safavid Empire Every empire that has ever been created constantly evolves. They will grow or they will diminish. Many empires cease to exist and some even start over under a different name. 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Carter stated these facts so that the reader would have a better gauge for how la rge the empire was when he begins to explain his purpose of the chapterRead MoreThucydides And Thucydides History And Warfare1645 Words   |  7 Pagesexplanations of the origins of conflict. Herodotus focuses on recalling the origins of the Ionian Revolt, the rise of the Persian Empire, and the Persian Wars with Greece, while Thucydides writes about the Peloponnesian War. M.I. Finely suggests, in the introduction of Thucydides’ book that Thucydides is complementing Herodotus by beginning where Herodotus left off (Finley, History of the Peloponnesian War p.16). Although these two historians approach the start of conflicts in different ways, it seemsRead MoreGreek and Roman civilizations1262 Words   |  6 Pagesmany great empires, but none have made a greater impact than the Greek and Roman empires. These empires began as small city-states, and grew to become the powerful empires we know today. 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The Ethics of Photos Major Principles of Ethics

Question: Describe about The Ethics of Photos for Major Principles of Ethics. Answer: Introduction Ethics are the major principles that reflect the values as well as norms of a society. In other words, ethics are simply the guidelines for its members for treating each other as per the accepted ideals with a fair approach (Djajadikerta Trireksani, 2013). The ethical consequences tend to be formed by the nature of service, profit, ownership, representation as well as creativity in the practice of photography (Keyzer et al., 2013). The ethical issues are often confused by the new technological application as well as exacerbated by the political ideology or cultural preferences and the individual ambition and personality. Therefore, this study aims to identify the ethical consequences associated with the digital photography (Scarles, 2013). There are numerous ethical issues in relation to the photography those must be considered in order to evaluate the resolution to address the consequences. The issues that will be the outcome of the evaluation should be taken seriously and mitigate d as soon as possible. This contemporary digital era has permitted people in order to gain as well as obtain the access to the digital photographs that belong to others. Online games, Mobile Technology, Social Media, Public Forums as well as the numerous other communications have provide allowance to people for utilizing images in various ways. ICT allows people for manipulating as well as changing the nature of few images by providing them a distinct purpose and a distinct meaning as well. Therefore, an ethical concern or consequences can be formed in this scenario. (Langmann Pick, 2014) The most effective victims of such unethical circumstances are the children and mostly the women. Therefore, crucial security issues are encountered those arise from the usage of the photos in the online environments such as the social media like Facebook and many others (Allen, 2012). Therefore, this study highlights all the crucial ethical issues of digital photography such as the ethical concerns of the intangible and intellectual property, images on social media, identity theft, access to the images, ownership and camera access using mobile devices, deception and manipulation using images and other ethical concerns. Discussion and Analysis The use of photographs in Digital world The digital photography is the form of photography that utilizes the cameras containing electronic photodetector arrays for capturing images focused by the lens as reversed to exposure on the photographic film (Van der Rijt Hoffman, 2014). The captured photographs are stored as well as digitalized as a computer file ready for the further digital printing, publishing, viewing as well as digital processing (Palacios-Gonzlez, 2015). Photography in the digital world is one of the various forms of digital imaging. The images that are available electronically can be uploaded to the websites or the social networking sites by the user. The user takes a photo with the help of digital camera or the present pictures can be scanned and then uploads the pictures to the internet. There could be various forms of pictures that can be transmitted or shared in the digital world. The Digital photographs are also made by the non-photographic equipment like the radio telescopes and computer tomography s canners. The photographs have huge utilities in the digital world (Quinn Manning, 2013). The uses of the digital photographs in the digital can be specified with the help of the benefits of the digital photography. The major advantage of the digital photography is that it is more cost effective than the film photography. On the other hand, digital photography helps in showing the instant previews. Apart from that, the digital photographs are very easy for sharing (Djajadikerta Trireksani, 2013). People can upload the digital photos to the websites, email those photos to their friends as well as store them on the CDs. apart from being easily stored and shared the technology for storing the photos are also cheaper and are more resilient to corruption. The technology hence has caught the fancy of the people. Most interesting fact regarding the photography in the digital world is that digital photography is more environment-friendly than the film photography. The digital photographs also take lesser space compared to the analog pictures and hence are more compact and user-friendly. The digital photos that have been taken can be easily modified and made more presentable compared to the film photogr aphy and hence has become more popular. Apart from being easier to implement and modify the photos are technology is also easier to use, more user-friendly and is also cheaper compared to the analog counterpart. There are several field where the digital photography plays an effective role (Keyzer et al., 2013). Digital photography is very significant in order to sell a particular product, in order to make insurance as well as an accident claim. Digital photographs are very effective in the clinical and medical world. Digital photographs are also very important for the driving license, passports and many other identity proofs (Scarles, 2013). Digital photos are also playing a very important role in the educational uses as well. Malicious use of the pictures The misuse or the malicious use of the digital photographs has become a crucial issue for people. The digital photographs are very significant in the digital world. However, along with this fact, it has also been seen that the digital photographs are being misused by people against which, an immediate action must be taken as soon as possible (Langmann Pick, 2014). The malicious use of the digital photos is simply a significant crime. Women as well as the teenagers are the general victims of such crime (Allen, 2012). The malicious uses of images have been rampant in schools and various offices around the world and draw criticism from everyone. Hence the practice which is not at all ethical should be discouraged and the users should be made more aware about the malice involving the digital image sharing over internet. On the other hand, in this digital age, the online platform or the social media are the most general platform through which such malicious use of the pictures are perfor med by the criminals (Van der Rijt Hoffman, 2014). Facebook is such an online platform over which such crime of misusing photographs is taken place. In this contemporary digital world, peoples lives have been dominated by the smart-phones that have changed the way people interact and most importantly the way people conduct, commence and end friendships and relationships (Palacios-Gonzlez, 2015). Hacking is such a criminal process through which the digital photos are misused the most. Image theft from the Facebook account of a user or the other social website is also a crucial misuse of image. The images stolen from the social media websites can be misused by applying those images in the pornography videos (Quinn Manning, 2013). In case of the business world, politics and other fields, the malicious use of photographs of the political leaders and business leaders can damage the impression of a political leader or party or harm the reputation or the revenue of a business organization (Djajadikerta Trireksani, 2013). In other words, the malicious use of the photographs can ruin all the aspects of personal and professional lives. Legal issues involved in malicious use of pictures As discussed earlier, the malicious use or the misuse of the photographs in this digital is the most vulnerable activity with the photographs. These malicious uses or the misuses of the digital photographs are completely unethical activity as per the legal aspect (Keyzer et al., 2013). Thus, there are several legal or the ethical issues incorporated with the malicious usage of the pictures in this digital world. Among the legal issues of the misuse of the pictures, security concern is the most important and significant legal concern of this matter (Quinn Manning, 2013). The malicious use of the digital pictures over the online platforms such as the Social Media like Facebook, Twitter and other online sources can mostly hamper the security or the privacy aspects of the victims account (Scarles, 2013). On the other hand, stealing images in the organizations can hamper the ethical aspects of the organizations. Due to the misuse of the pictures in the organizations made by the hackers o r the other illegal accesses, it would result in the loss of the employees (Langmann Pick, 2014). Apart from that, the misuse of the digital photographs in making the pornographic videos is completely illegal while the photos are literally stolen from peoples social media account without their concerns (Allen, 2012). On the other hand, it is also the fact that the pornography is not legal in most of the countries in all over the world. Apart from that, the legal issues of the malicious use of the photographs can create a negative impact on the professional as well as the personal lives of people (Palacios-Gonzlez, 2015). This illegal access of the photographs can ruin the political, educational as well as business activities due to which the general people are most affected. Ethical issues involved with the use of the digital pictures There are several ethical issues associated with the digital images, like the manipulation of the images, image theft, plagiarism of the photo, etc. In the digital era of photography photos are captured in every second and shared worldwide between wide ranges of individuals (Barbovschi,Green Vandoninck, 2013). The introduction of digital images has also introduced various tools for the manipulation of the image, using which the image can be altered. This turned into an ethical issue and the tool can be used to manipulate and influence people. The digital images should be used for the display of the reality but tampering the image is acceptable to certain limits and exceeding the limit can change the originality of the image leading it to an ethical issue (Greensmith Green, 2015). The digital images can be stolen and sold over the internet without the permission of the owner. The stolen image can be misused and manipulated to destroy the personality of a person or expose negatively t o the society. Plagiarism of the photo is another ethical issue associated with the digital image; it is the situation when someone borrows the idea of another photographer and uses it for his image (Hannay Baatard, 2011). It is a most common case in the recent times where the photographer steals the idea and tries to perform better and often succeed in doing so. In the fashion industry most of the images on the cover pages of the magazine are altered digitally. But sometimes they are altered drastically making the model looking completely different from the real life (ORourke, 2011). Thus are ethical issues regarding the digital photography, the images should be altered or retouched that is acceptable to the society but going beyond the limits makes it an ethical issue. Use of pictures of children Most of the people having children at their home posts images of their children or the persons at the schools posts pictures of the students on different social media sites. These pictures can adversely cause embarrassment for someone (Students) in short term or long term (Livingstone, 2014). The reason behind this is, anyone can edit and misuse the uploaded photos on the social media. In addition to this the use of photo tagging feature which is used to identify people present in the picture can also cause breach in the privacy of an individual (Staksrud, lafsson Livingstone, 2013). Therefore, it is important for the individuals and school authorities to protect their children and students from the adverse effects as a result of publishing their picture. To do this the parents can upload pictures that focus on the group activities. In addition to this parents also consider controlling the availability of the pictures to different group of audiences. Students must not take, use, sha re and publish images of other students (Staksrud, lafsson Livingstone, 2013). Therefore, while posting or sharing the pictures of the children then, two things must be taken care of. The amount of information the photo or the picture providing, the consent of the children. This is mostly about the information that a child wants to or ignores to see it online. Difference between the use of pictures in websites and social media Today different site and social media platforms are mainly populated with digital images to convey information, messages, and to assist people to understand reality. The images are also used to change the existing mindset of the people. The pictures used all around the world for publicizing, advertising and giving momentum to organizations around the world. In early periods the images are manipulated with the chemicals which were detectable. But today when the pictures are manipulated and are posted on an informative website then it can mislead the viewers (Bobkowski Smith, 2013). This will consequently lead the viewers to get a wrong and manipulated concept about any incident, object or personality, which has even resulted in many cases of suicide and depression. Today the there are several digital tools are available for manipulation of the pictures. The one that is most famous among the users is the Photoshop created by Adobe. These unintended changes in the pictures can lead to visual deception. In addition to this when the images are manipulated and posted on the different social media platforms with the intention to entertain people may hurt some one's emotion (Hazell, 2011). Most adversely, if someone creates any image (Trolls) depicting a public figure doing stupid things, then it will be a reason for public unrest created by the followers of that specific personality. In addition to this if someone creates any image or picture by disrespecting the faith or religious belief of any community then, it will also become the reason of religious riots in any country (Livingstone, 2014). This happens due to the most special feature of a picture or photograph to generate an immediate emotional response either for an event (for a personality, object) or against any event. Even though the increasing awareness about the different manipulation techniques is frequently associated with loss of trust on the different news portals and websites, but it is not the correct time to say that the use of the images and photographs to convey messages must be abolished due to the manipulation of the images (Stein, 2009). Here it can be said that as the internet is considered as the major source of knowledge and information, therefore the owners of the websites or the policy makers of the websites and social media platforms must review the different images and photo posts that are uploaded by different users (Hazell, 2011). This will help in maintaining the faith of people which are challenged by the possibilities of different seamless manipulation techniques. The ownership of the images posted on Social Networking sites The images that are posted on the social networking sites are the property of the owner, and the copyright should belong to the creator. The owner of the image have the right to copy, use or distribute the image but when the image is posted on the social networking site the site gets a license to use the image for their commercial activity and can share the image with other individuals also (Hannay Baatard, 2011). For example, Twitter or Facebook can use the uploaded image of a person for their commercial gains which can be done by obtaining likes and shares of the images. The photos that are posted on the site can be easily downloaded from the websites, and as has been mentioned in the previous section the images can be used for a variety of malicious practices that can create a problem for the person. The Twitpic service of Twitter is riskier than Facebook; it can access the deleted photos of the users. This means that they can use the image even after the termination of the license (ORourke, 2011). Twitter can also give access permission to different users and gain profit from the image without paying the user the profit percentage. Thus the social media users must be aware of the terms and conditions of the site before posting the photo to their websites. The problem regarding the ownership of the image can be an ethical issue for the social networking media (Green, 2013). The issue should be mitigated such that the users feel free to post their images, and the sharing of the license should be limited to the social networking site, and it should not be redistributed to the other users (Cook, 2010). There is a risk associated with the other users of the social networking that they can misuse the images for performing illegal activities. The security issues related to photos used on Social Networking Sites (SNS) There are various security concerns and little advantages associated with the sharing of the photos over the internet. The sharing of the pictures could be in any website or the SNS, which makes the pictures available to the digital environment (Cook Kumar and Unmar-Satiah 2015). The major security concerns are identity theft, sexual predators, stalking, victimization, and surveillance. The lesser known advantages are fame and employment. The identity theft affects millions of internet users around the world every year. The impact of such act results in loss of countless hours and money to the whole system. The primary reason behind such act is a lack of knowledge regarding the online identity and the growing trust and comfort of people on the around the social networking sites. The lack of standardization and policing is another reason behind such malicious practices. The social networking sites generate revenue by helping in targeted advertisement (CrippsStanding and Fanning 2015). The sites shared the personal information about the user and based upon the information the companies advertise on the home page of the user profile. Since there is a lack of government oversight, user education, and industry standards, the user is not well educated about the issue that is associated with sharing of data over such websites. Hence sharing of sensitive data and photos are rampant and has led to the case involving identity t hreats. A recent algorithm patented by Google can rate the user influence of such site which will encourage the data sharing of the users. There are millions of users around the world who use SNS which include the criminal and persons with a criminal mentality. The users of such websites should understand that the photos and the data they share are available to them, and such sensitive information is prone to threats from both internal and external sources equally. The validity of Photo IDs in todays environment A photo ID card is a document used for identification of the person. The ID card contains basic information like the Photo of the person, name, and address. The main motive of using the ID cards is for face to face identification and authentication. Availability of photos at several places can be a serious threat to one's identity. Fake photo identities have always been a problem to the society, and the availability of photos over the internet make the process of faking even easier (Dhouha et al. 2014). The social networking encourages the user to share maximum information about them, which can help the friends to have a clear picture about What? When? Why? about the user. Although the social networking has helped the world to be a very compact place, the shared information can be seen by other internet users too. The sensitive information about the user can be accessed in a jiffy ((Bobkowski Smith, 2013)). Since the photo ID cards contain only necessary information about the user which can be readily accessed through the Internet, generation of ID cards have become easier. Hence it can be understood that the validity of ID cards have become big questions. Hence the governments around the world are going for multiple authenticities, which consist of both physical and the digital data (Johnston et al. 2013). The magnetically coded ID cards have become a trend in industries which has both physical and electronic data for authentication. Geocaching and Online Images Geocaching, which is similar to the game of letterboxing, can be used for many purposes such as gaming or making the package available to selective people. This technique is mainly used in the public domain for a treasure hunt. The pictures of the site and the coordinates are shared, and the treasure hunter has to go and search for the package at the indicated location. The pictures, in this case, are used as clues that could be used for guiding the hunter (Management Association ed. 2013). The photos that are used to indicate the physical location are most important part of Geocaching. It acts as the reference for the treasure hunt, and the hunters are lured by the pictures. The more convincing the pictures are the hunters are more lured towards the location (Tonge et al. 2011). The game that recently has caught the attention of people name Pokmon Go uses the same concept for hunting down the Pokmons. Geocaching has caught the attention of the criminal as they try to lure the gamers to a remote location and loot them. There had been incidents of crimes that involve shooting (Trial begins in the shooting of boy, 13, geocaching with his father The Mercury News, 2016). There are various websites that are open to the user which create a community for the players. These communities can be accessed by users from different places, and these users can upload various tasks for the fellow users making the game the perfect recipe for disaster. The criminal can use these platform s to lure the gamers into a trap and do things that have always been condemned (Valli and Hannay 2010). Hence it always suggested that the sources of such treasure hunts be always checked before leaping into it. Conclusion The credibility of every user can be guaranteed, any information in such hand should be treated as a threat. The networking site such as Instagram allows users to upload picture instantaneously thus showing the location and picture of the user, through which the general idea about the user can be grasped and used against them. As it has been aptly said that a picture is worth thousands of words and such information in wrong hand is a serious threat. In this article, the various threats that an internet user faces due to sharing of images and photos on the internet has been discussed in detail. The various aspects that have been discussed in the segment are publishing photos in the digital world its impact on the user and the consequences. In the next section, the various malicious uses of the picture have been discussed in detail for making the user more aware of the consequences that they can suffer due to sharing of images in various internet platforms. The next section contains th e impact of malicious practices on the defaulter have been presented to prevent the users of the internet from committing such crimes. Then the ethical issues of sharing the different types of the picture have been discussed, which will help in understanding the impact of sharing pictures with the community. The subsequent sections deal with the impact of sharing the picture of children and the ownership of the pictures in case of deceased users. Sharing of the picture of children can have an impact on the child as the future of the children is yet to unfold. In this scenario, the rights of the owner have been discussed. Finally, the security aspects of the pictures have been shared, which contains the issue related to sharing of pictures in SNSs, the need for a better security measure to prevent identity threats and the present genre of games that uses Geocaching to lure the user into traps. References The Mercury News. (2016). Trial begins in the shooting of boy, 13, geocaching with his father Mercurynews.com. Retrieved 9 September 2016, from https://www.mercurynews.com/2011/09/28/trial-begins-in-shooting-of-boy-13-geocaching-with-his-father/ Valli, C. and P. Hannay (2010). Geotagging Where Cyberspace Comes to Your Place Ryan, M., Ogilvie, M., (2011),Uncovering hidden meanings, values and insights through photos.E-Journal of Business Research Methods,9(1),25-34,Reading, UK. Tonge, J., Moore, S.,Ryan, M., Beckley, L., (2011),Using photo-elicitation to explore place attachment in a remote setting.The Proceedings of the 10th European Conference on Research Methodology for Business and Management Studies,629-637,Reading, United Kingdom. Cripps, H.,Standing, C., Fanning, S., (2015),Does social media work in business-to-business marketing context?.Proceedings of the 2nd European Conference on Social Media ECSM 2015,89-95,Reading, UK. Management Association ed., (2013).K-12 Education: Concepts, Methodologies, Tools, and Applications: Concepts, Methodologies, Tools, and Applications. IGI Global. Dhouha, A.F., Camenisch, J., Ignatenko, T., Johnstone, M.N., Koster, P., Lange, B., Petkovic, M., Sommer, D. and Zic, J., (2014). Authentication and authorisation in entrusted unions. Innocent, T. and RILE, M., (2014). The augmented bush walk: adaptation in cross-media ecologies. InxCoAx 2014(pp. 234-247). Universidade do Porto. Johnston, J., Keyzer, P., Holland, G., Pearson, M.L., Rodrick, S. and Wallace, A., (2013). Juries and social media: a report prepared for the Victorian Department of Justice.Juries and Social Media: A Report Prepared for the Victorian Department of Justice, pp.1-30. Cook, D.M., Kumar, A. and Unmar-Satiah, C., (2015). Loyalty cards and the problem of CAPTCHA: 2nd tier security and usability issues for senior citizens. Allen, Q. (2012). Photographs and stories: ethics, benefits, and dilemmas of using participant photography with Black middle-class male youth.Qualitative Research, 1468794111433088. Djajadikerta, H., and Trireksani, T., (2013),Executive Perceptions of CSR.Socially Responsible and Sustainable Business Around the Globe: The New Age of Corporate Responsibility,70-79,Champaign, Illinois, USA. Keyzer, P., Johnston, J., Pearson, M., Rodrick, S.,and Wallace, A., (2013),The Courts and Social Media: What Do Judges and Court Workers Think?.Judicial Officers' Bulletin,25(6),47-51,Australia. Langmann, S., and Pick, D. (2014). Dignity and ethics in research photography.International Journal of Social Research Methodology,17(6), 709-721. Palacios-Gonzlez, C. (2015). The ethics of clinical photography and social media.Medicine, Health Care and Philosophy,18(1), 63-70. Quinn, S. M. F., and Manning, J. P. (2013). Recognizing the ethical implications of the use of photography in early childhood educational settings. Contemporary Issues in Early Childhood,14(3), 270-278. Scarles, C. (2013). The Ethics of Tourist Photography: Tourists' Experiences of Photographing Locals in Peru.Environment and Planning D: Society and Space,31(5), 897-917. Van der Rijt, R., and Hoffman, S. (2014). Ethical considerations of clinical photography in an area of emerging technology and smartphones.Journal of medical ethics,40(3), 211-212. Barbovschi, M.,Green, L., Vandoninck, S., (2013),Innovative approaches for investigating how children understand risk in new media: Dealing with methodological and ethical challenges.,United Kingdom. Bobkowski, P., and Smith, J. (2013) "Social media divide: characteristics of emerging adults who do not use social network websites",Media, Culture Society, 35(6), pp. 771-781. Cook, D.M. (2010) "The Use of Governance to Identify Cyber Threats Through Social Media," in The 1st International Cyber Resilience Conference, Perth, Western Australia: secau - Security Research Centre, Edith Cowan University, 2010, pp. 31-40. Green, L., (2013),Analysing data from innovative designs.Innovative approaches for investigating how children understand risk in new media: Dealing with methodological and ethical challenges,ECU Kids Online. Greensmith, G.,Green, L., (2015), Reporting random mass shootings: The copycat effect?. Ethical Space: the international journal of communication ethics, 12(3/4), 73-80, Suffolk, UK. Hannay, P. and G. Baatard (2011). GeoIntelligence: Data Mining Locational Social Media Content for Profiling and Information Gathering. The 2nd International Cyber Resilience Conference. C. Valli. Duxton Hotel, Perth, Western Australia, secau - Security Research Centre, Edith Cowan University: 29-37. Hazell, T. (2011) "Use social media websites responsibly, urges NMC president Tony Hazell",Nursing Standard, 25(41), pp. 26-26. Livingstone, S. (2014) "Developing social media literacy: How children learn to interpret risky opportunities on social network sites",Communications, 39(3). ORourke, S. (2011). Empowering protest through social media. The 2nd International Cyber Resilience Conference. C. Valli. Duxton Hotel, Perth, Western Australia, secau - Security Research Centre, Edith Cowan University: 47-55. Staksrud, E., lafsson, K. and Livingstone, S., (2013). Does the use of social networking sites increase childrens risk of harm?.Computers in Human Behavior,29(1), pp.40-50 Stein, L. (2009) "Social Movement web use in theory and practice: a content analysis of US movement websites",New Media Society, 11(5), pp. 749-771.

Othello Essays (1453 words) - Othello, Iago, Emilia, Michael Cassio

Othello Othello, written by William Shakespeare is the story of Othello, the protagonist and tragic hero of the play. A Moor commanding the armies of Venice, he is a celebrated general and heroic figure whose free and open nature will enable Iago to twist his love for his wife Desdemona into a powerful jealousy. Iago is Othello's ensign, and Shakespeare's greatest villain. His public face of bravery and honesty conceals a Satanic delight in manipulation and destruction. Passed over for a promotion by his commander, he vows to destroy the Moor. If Iago is an artist of evil, then this scene is the finest canvas he paints. This is the crucial moment in the play, the scene where he, , deceives Othello and induces him to fall. He does so by expanding on the tactics used in prior scenes. Once the seed of doubt is planted in the Moor's mind with a quick Ha! I like not that (III.iii.35) (when they come upon Desdemona and Cassio) and a few probing questions about the ex-lieutenant's relationship to Othello's wife, Iago retreats into the guise he has adopted. He becomes honest Iago, again, as in the brawl in Act II, scene ii--the reluctant truth-teller who must have unpleasant news dragged from him by a determined Othello. The honesty suggested by his reluctance to speak is reinforced by the moralizing tone that he takes with his commander. Iago actually lectures Othello, warning him against jealousy (the green-eyed monster) and insisting that he will not speak slander: he that filches from me my good name / Robs of that which not enriches him / And makes me poor indeed (III.iii.158-61). At the same time, he plays upon the insecurities of the honest, noble African in sophisticated, decadent Venice by lecturing Othello on how Venetian women are deceitful and treacherous by nature. The overall effect is to pour verbal poison in his master's ear--not by lying, but by flavoring truth with innuendo. Othello will later declare that he is not easily jealous, and that assessment of his character seems to be shared by most of the figures around him in the play. The critical response is mixed--some critics insist that his claims to be innocent of jealousy are merely self-justifying, and certainly he slips easily into assuming his wife to be unfaithful. Other critics make the distinction between an inner, self-created jealousy, which he seems to lack, and a deep insecurity and trusting nature, as Iago puts it, which allow a clever manipulator to plant seeds of doubt. Behind his insecurity lies a man uneasy with his place in Venetian society: he may have married a white woman, a daughter of a Senator, but can he keep her? The seizure of the handkerchief is a great coup for Iago in his quest to destroy Othello, and he is aided by his wife, who apparently has no scruples about betraying her mistress in small matters. Shakespeare will eventually transform Emilia into a voice of moral outrage, and by the final scene the audience will applaud her role in Iago's destruction, but for now it is worth noticing that she is only Iago's accomplice. It will take a great shock to inspire outrage against him--a shock which comes too late. The scene ends with Iago triumphant, named as lieutenant (the rank to which he aspired from the beginning) to a man bent on destruction, and ready to join in that destruction himself--because in killing Cassio and Desdemona, Othello is killing himself. And that, of course, has been Iago's goal from the beginning. Othello's wild, violent behavior in front of Lodovico, in which he strikes his wife and abuses her for no apparent reason, demonstrate the perversion of order that Iago has brought about. There is no one to halt Othello's lawlessness, because he himself is the law in Cyprus. Othello's accusations and refusal to accept Desdemona's denials are brutal and unfair, but his language recovers some of the nobility that it had lost in previous scenes. Iago-like curses are replaced by sorrowful laments for what has been lost, and the audience is reminded the heroism and dignity that Othello possessed at the beginning of the play. His cry O, thou weed, / Who art so

Forensic Dna Profiling free essay sample

In trials where a defendant may be given a life or death sentence, is it reasonable to place so much faith in genetic forensic results? I believe that although DNA profiling is a great tool for identifying suspects and victims, at our current technological state, we should use it as supplemental evidence rather than assume it is 100% foolproof. DNA is 99. 9% identical throughout all human beings (Lander). So how is it possible that DNA is used as evidence in the courtroom? DNA gathering is less invasive than a blood test, as a simple cheek swab can be sufficient for analysis. The tiny fraction of DNA that is unique to individuals is what is used in forensic testing. In the early stages of DNA forensics, restriction fragment length polymorphisms (RFLP) were used by digesting DNA with restriction enzymes and then analyzing the resulting fragment lengths which were unique to individuals (Davidson). One of the main techniques used nowadays is the combination of PCR and short tandem repeats. We will write a custom essay sample on Forensic Dna Profiling or any similar topic specifically for you Do Not WasteYour Time HIRE WRITER Only 13.90 / page PCR, or polymerase chain reaction, is a method used to amplify sequences of DNA. By amplifying specific polymorphic regions of DNA, unique number of repeats at specific locations can be assigned to individuals (Human Genome Project). DNA analysis has become the most advanced method of identification, replacing fingerprints. Due to its accuracy, DNA profiling in forensics not only has the power to positively identify criminals, but also make sure an innocent person is not wrongly convicted. Moreover, in some cases where the victims are hard to identify, DNA analysis can give these victims an identity (Thelin). Due to its accessible and hardy nature, samples of DNA are sometimes the only evidence that is available for collection, and combined with its accuracy, make it a very valuable asset in the courtroom. Efforts are constantly underway to improve the efficiency and accuracy of these techniques, but these genetic forensic applications, like any other test, is by no means 100% accurate. These techniques above indeed offer unique supplemental evidence, but I believe more time and work is needed in order to make DNA forensics more invaluable in the courtroom. This includes expanding current national databases and improving upon existing technology and techniques. There needs to be consideration for the matching of family members such as distant relatives or twins. For example, in January of 2007, a perfect DNA match at 13 regions was discovered in only 30,000 samples (Felch). Forensic DNA analysis does not only play a role in matching a certain individual to a crime, but also can be used to prove innocence also. As a result, though the chance of having a match with a relative or twin may be very small, the risk of human error in laboratories is significantly larger. Currently, DNA analysis is not completely automated, and human errors can play a huge factor in the validity of DNA evidence. Contamination of samples, which may turn a positive identification into a negative one, is a key problem area in the processing of DNA samples. Furthermore, there have also been cases of planted fake DNA evidence, and the improper or incomplete collection of DNA may also question the validity of the evidence and raise privacy concerns (Pollack). I believe that although genetic evidence can often make a great case, it should always be viewed with skepticism. If other evidence in the case raises doubts or if the collection and analysis was not error-free, then it should not be taken as definite. The increasing popularity of forensics in media such as TV shows, which often represent DNA profiling and forensic in an oversimplified manner, has given the public a skewed view of real life forensics. If DNA is presented as convincing evidence, then I believe the jury should be informed of the possible risk factors associated with genetic analysis. A convincing case should be made through a combination of evidence, rather than just relying on DNA itself. As the progress of science and technology continues to reach new heights, there is no doubt that new and more efficient techniques will be developed that may address many of the concerns that current forensic DNA profiling poses today. This is not to say that at its current stage forensic DNA should be taken lightly. However, with lives and innocence at stake, everything, including genetic analysis, should be carefully reviewed and tested thoroughly. As with any relatively new technology, there are certainly going to be issues and roadblocks. However, forensic DNA profiling is here to stay, and as more work and effort is placed into its research and development, justice will be served to the guilty, keeping criminals in jail and the innocent free.

17c PAPER

17c PAPER 17c PAPER 4. If the Fourteenth and Fifteenth Amendments guaranteed equal protection of the laws and the right to vote, why was a Civil Rights movement necessary in the 1950s and 1960s? What major factors and events led up to the Civil Rights movement and what were the gains and losses experienced by those participating in the movement? Gender and racial equality injustice in the United States against African Americans dates backs to long ago in the early colonization and building of the nation. After the Civil War, the United States underwent a Reconstruction Era in which the Thirteenth, Fourteenth and Fifteenth Amendments were added to the Constitution. The Fourteenth and Fifteenth Amendment guaranteed African Americans equal protection under law and guaranteed him or her the right to vote but government authority lacked support and push to enforce these. The Civil Rights movement was necessary in order for African Americans to achieve equality within a white dominated society. Moreover, the Civil Rights movement served as a catalyst for African Americans to secure their political rights by gaining concrete legislation. Legislation in the Black community meant the support of both Congress and the President. African American perceived this support as a milestone because Congress and the President could enforce laws in favor of integration. African Americans viewed integration as the root to equality because integration meant that black citizens and white citizens would receive equal treatment and therefore the opportunity to pursue The Civil Rights movement was successful through political organizations, direct action protests and changing speeds at which presidents addressed inequality. During this time that dates back to the late 1800s, there was a lot of hostility in the South against the new politics and the Reconstruction providing opportunities for African Americans. Not all Southern Whites agreed with this and as a result, many angry men took part in horrifying acts such as lynching in great quantities. Founded as a way to defend African Americans that were tormented and a goal of actually securing constitutional rights identified in the Thirteenth, Fourteenth and Fifteenth Amendments, the National Association for the Advancement of Colored People comes together in 1909. The NAACP was and is still a major component of Civil Rights today. When it formed, the NAACP was able to identify and show this mistreatment and injustice that African Americans received on a day-to-day basis under a society that this. This political organization began in the 1900s and it persevered on for many years with strong beliefs in equal treatment, justice and liberty for all races. The Civil Rights movement began to become recognized once again in the mid 1950s. Civil Rights activism was still present between this time and the 1900s but with the conflicts between the United States among Nations, it was not until the Post Cold War era that the fight for justice and equality for colored was reborn. The Civil Rights reawakening happened with the Brown vs. Board of Education challenged the segregated schools in the South and the goal with this case was to let the states understand that doing this to there children, separating them based on race and color was unconstitutional and resisting. With the Brown vs. Board of Education case, the African American community was able to take the White Southern views of segregation in the state of Kansas and challenge them in Supreme Court. This case challenged the idea of gradualism because although the Amendments that protected all under the same equality, prevous presidents had had the mentality of letting the segregation slowly fribble away but it was seen here that some this idea would not work. The NAACP political organization strongly supported this as it had also began to breakdown and identify the racism and segregation found in schools and the Brown vs. Board of Education case seemed to be a

Environmental Psychology Article Analysis Research Paper

Environmental Psychology Article Analysis - Research Paper Example ology by Mohay and Forbes which is entitled â€Å"Reducing the Risk of Posttraumatic Stress Disorder in Children Following Natural Disasters.† The article discussed the posttraumatic stress disorder (PTSD) that can affect children due to the occurrence of natural disasters. Included in the objectives of the paper were the examination of the risk and protective factors and the application of the strategies in schools to resolve cases of PTSD (Mohay and Forbes, 2009, p.179). The subject of the research is relevant to the present era wherein numerous natural disasters are affecting the human civilization. The said disasters also come in different forms such as typhoons, tornado, tsunami, volcanic eruptions and floods. Preparedness not only in terms of shelter and basic needs but also in the emotional aspect is important. The focus of the study can be considered essential due to the fact that the children are the most susceptible to the effects of natural disasters specifically ba sed on the risk factors. The abstract of the paper presented pertinent information that summarized the content of the paper. The background information had also been helpful based on the definitions of the concepts and terms that were defined in the said part of the research paper. In addition, important and substantial information and research results of prior studies had also been included (p.179-82). The discussion of the risk factors followed. The different risk factors and resolutions that had been presented by the authors are considered important in the improvement of the consciousness regarding the issue. The risk factors that are related to PTSD included in the study were age, personality, extent of exposure to natural, amount of damage to property and infrastructure, witnessing the death or injury of others or perceiving a threat to own life (p.182-5). The age as a risk factor had been connected to the cognitive level of development of a person. For that matter, a child

Managing Conflicts in Organizations Term Paper Example | Topics and Well Written Essays - 1250 words

Managing Conflicts in Organizations - Term Paper Example It would not be unfair to say that conflict is inevitable amongst human beings. The constant struggle to get hold of status, resources, power etc amongst humans often results in a form of social interaction called conflict. Thus, conflict can formally be defined as: â€Å"A process which begins when an individual or group perceives differences and opposition between itself and another individual or group about interests and resources, beliefs, values, or practices that matter to them.† (Digirolamo) In the same way that conflicts are inevitable in everyday life, they are also inevitable in organizations. Especially in modern organizations wherein factors such as constant change, employee diversity, team based structures etc make conflict an ever-present. Conflict, however, is not necessarily a bad thing and can help get the best out of individuals within the organizations. Organizations must therefore make sure that they do not discourage conflict but rather manage it smartly s o that it can work to its advantage. Thus, conflict can be looked at in different ways in organizations: Conflict as war – When parties treat conflict as a must-win war. Conflict as opportunity – When parties use the conflict as an opportunity to be more creative, to grow and to improve on what they already are. Conflict as journey – When parties use the conflict as a search for common ground. The first view of conflict is a win-lose situation. Such a situation is not good for the organization in any way because such conflict is destructive. The other two views on the other hand are constructive in nature and are desirable for organizations because they create win-win situations and help the organization get the best out of its employees. (Kreitner & Kinicki, 2008). Organizations should therefore make sure that its employees treat conflict in the right manner and it is for this purpose that they employ conflict management practices. Conflict management practices involve many different strategies which can be used by organizations to manage conflicts effectively. Some of these strategies are discussed below. The first technique that managers can use is fostering functional conflict. Functional conflict can be defined as the kind of conflict which is beneficial to the organization’s interest. (Kreitner & Kinicki, 2008) Managers looking to infuse their decision making teams with creativity and passion very often look towards stimulating functional conflict. There are two ways of doing this. The first method is to fan the naturally arising conflicts between different parties. This method, however, is very unreliable and may end up stimulating dysfunctional conflict. The other method is to employ programmed conflict. Programmed conflict can be defined as â€Å"conflict that raises different opinions regardless of what the managers personally feel about the issue.† This method requires disciplined role playing by everyone involved (Kreitner & Kinicki, 2008). The two best methods of programmed conflict are devil’s advocacy and dialectic decision method. Devil’s Advocacy is the technique in which someone is assigned the role of a critic and is told to air all possible objections to an idea. (Kreitner & Kinicki, 2008). Dialectic Decision Method simply requires fostering a debate of opposing points of views prior to making a decision in order to better understand the whole issue (Kreitner &

Critically discuss the the extend to which attitudes towards the Essay

Critically discuss the the extend to which attitudes towards the mentally ill improved during the nineteenth century - Essay Example This responsibility slowly occurred during the early and mid-1800s. This new treatment of psychologically unstable patients marked the beginning of a new recognition that irregular psychological states and behaviour patterns were the outcomes of possibly treatable illnesses. The following paper critically discusses the degree to which attitudes towards the mentally ill improved in the nineteenth century UK. To understand this degree, the paper will begin by briefly discussing the attitude of the UK health industry and society towards the mentally ill several decades before 1800. The 1800s saw the slow emergence of a humane attitude towards the mentally unstable, but geographic and institutional separation would persist in the treatment of mental disorders. Before the nineteenth century, the United Kingdom health department, together with society, did not take psychological illnesses seriously. Before the deployment of ‘mad doctors,’ there were no medical facilities for the mentally ill. As a result, doctors often isolated a psychologically unstable patient from the rest by ensuring the patient was homebound.1 Another indication of the unserious treatment of mentally unstable patients was their relatives’ denial of the illness. Physicians who recommended mentally ill patients to remain at home often fuelled this denial by family members. In spite of a more compassionate attitude called ‘moral treatment’ having arisen between 1790 and 1800, the entire UK health department was far from treating the mentally ill morally.2 The construction of asylums did not assist in improving this attitude either. Instead, asylums simply showed society that the government had recognised mental problems as treatable issues , but not through conventional methods. The main purpose of moral treatment was to diminish external, bodily coercion, which was not evident until the onset of the

Effects of Exercise on the Human Body

Effects of Exercise on the Human Body Exercise represents one the highest levels of extreme stresses to which the body can be exposed. Exercise physiology is the study of the function of the human body during various acute and chronic exercise conditions. These effects are significant during both short, high intensity exercise as well as with prolonged strenuous exercise such as done in endurance sports like marathons, ultramarathons, and road bicycle racing. In exercise, the liver generates extra glucose, while increased cardiovascular activity by the heart, and respiration by the lungs, provides an increased supply of oxygen. When exercise is very prolonged and strenuous, a decline, however, can occur in blood levels of glucose. In some individuals, this might even cause hypoglycemia and hypoxemia. There can also be cognitive and physical impairments due to dehydration. Another risk is low plasma sodium blood levels. Prolonged exercise is made possible by the human thermoregulation capacity to remove exercise waste hea t by sweat evaporation. This capacity evolved to enable early humans after many hours of persistence hunting to exhaust game animals that cannot remove so effectively exercise heat from their body. In general, the exercise-related measurements established for women follow the same general principles as those established for men, except for the quantitative differences caused by differences in body size, body composition, and levels of testosterone. In women, the values of muscle strength, pulmonary ventilation, and cardiac output (all variables related with muscle mass) are generally 60-75% of the exercise physiology values recorded in men. When measured in terms of strength per square centimeter, the female muscle can achieve the same force of contraction as that of a male. The functions of muscle tissues assume roles in homeostasis, as follows: Excitability Property of receiving and responding to stimuli such as the following: Neurotransmitters: Acetylcholine (ACh) stimulates skeletal muscle to contract, electrical stimuli: Applying electrical stimuli between cardiac and smooth muscle cells causes the muscles to contract, Applying a shock to skeletal muscle causes contraction, Hormonal stimuli: Oxytocin stimulates smooth muscle in the uterus to contract during labor.Contractility Ability to shorten. Extensibility Ability to stretch without damageElasticity Ability to return to original shape after extensionThrough contraction, muscle provides motion of the body (skeletal muscle), motion of blood (cardiac muscle), and motion of hollow organs such as the uterus, esophagus, stomach, intestines, and bladder (smooth muscle).Muscle tissue also helps maintain posture and produce heat. A large amount of body heat is produced by metabolism and by muscle con traction. Muscle contraction during shivering warms the body. Skeletal muscle consists of fibers (cells). These cells are up to 100 Â µm in diameter and often are as long as the muscle. Each contains sarcoplasm (cytoplasm) and multiple peripheral nuclei per fiber. Skeletal muscle is actually formed by the fusion of hundreds of embryonic cells. Other cell structures include the following:Each fiber is covered by a sarcolemma (plasma membrane). The sarcoplasmic reticulum (smooth endoplasmic reticulum) stores calcium, which is released into the sarcoplasm during muscle contraction. Transverse tubules (T tubules), which are extensions of the sarcolemma that penetrate cells, transmit electrical impulses from the sarcolemma inward, so electrical impulses penetrate deeply into the cell. Besides conducting electricity along their walls, T tubules contain extracellular fluid rich in glucose and oxygen.The sarcoplasm of fiber is rich in glycogen (glucose polymer) granules and myoglobin (oxygen-storing protein). It also is rich in mitochondria. Each fibe r contains hundreds to thousands of rodlike myofibrils, which are bundles of thin and thick protein chains termed myofilaments. From a cross-sectional view of a myofibril, each thick filament is surrounded by a hexagonal array of 6 thin filaments. Each thin filament is surrounded by a triangular array of thick filaments.myofilaments are composed of 3 proteins: actin, tropomyosin, and troponin. Thick myofilaments consist of bundles of approximately 200 myosin molecules. Myosin molecules look like double-headed golf clubs (both heads at the same end). The heads of the golf clubs are called myosin heads; they are also called cross-bridges because they link thick and thin filaments during contraction. They contain actin andadenosine triphosphate (ATP) binding sites. Myosin heads project out from the thick filaments, allowing them to bind to the thin filaments during contraction. Actin is a long chain of multiple globular proteins, similar in shape to kidney beans. Each globular subunit contains a myosin-binding site. Tropomyosin is a long strand of protein that covers the myosin-binding sites on actin when the muscle is relaxed. Troponin is a polypeptide complex that binds to tropomyosin, helping to position it over the myosin-binding sites on actin. During muscle contraction, calcium binds troponin, which causes tropomyosin to roll off of the myosin binding sites on actin. A muscle action potential travels over sarcolemma and enters the T tubules, causing the sarcoplasmic reticulum to release calcium into the sarcoplasm. This triggers the contractile process.Myosin cross-bridges pull on the actin myofilaments, causing the thin myofilaments of a sarcomere to slide toward the centers of the H zones.Deep fascia is a broad band of dense irregular connective tissue beneath and around muscle and organs. Deep fascia is different from superficial fascia, which is loose areolar connective tissue.Other connective-tissue components (all are extensions of deep fascia) include epimysium, which covers the entire muscle; perimysium, which penetrates into muscle and surrounds bundles of fibers called fascicles; and endomysium, which is delicate, barely visible, loose areolar tissue covering individual fibers (ie, individual cells).Tendons and aponeuroses are tough extensions of epimysium, perimysium, and endomysium. Tendons and aponeuroses are made of dense regular co nnective tissue and attach the muscle to bone or other muscle. Aponeuroses are broad, flat tendons. Tendon sheaths contain synovial fluid and enclose certain tendons. Tendon sheaths allow tendons to slide back and forth next to each other with lower friction. Tenosynovitis is inflammation of the tendon sheaths and tendons, especially those of the wrists, shoulders, and elbows. Tendons are not contractile and not very stretchy; furthermore, they are not very vascular and they heal poorly. Nerves convey impulses for muscular contraction. Nerves are bundles of nerve cell processes. Each nerve cell process (ie, axon) divides at its tip into a few to 10,000 branches called telodendria. At the end of each of these branches is an axon terminal that is rich in neurotransmitters.Blood provides nutrients and oxygen for contraction. An artery and a vein usually accompany a nerve that penetrates skeletal muscle. Arteries in muscles dilate during active muscular activity, thus increasing the supply of oxygen and glucose.A motor nerve is a bundle of axons that conducts nerve impulses away from the brain or spinal cord toward muscles. Each axon transmits an action potential (ie, nerve impulse), which is a burst of electricity. The nerve impulse travels along the axons at a steady rate, like fire travels along a fuse; however, nerve impulses travel extremely fast. Each axon has 4-2000 or more branches (ie, telodendria), with an average of 150 telodendria. Each separate branch suppli es a separate muscle cell. Thus, if an axon has 10 branches, it supplies 10 muscle fibers. Small motor units are for fine control of muscles; large motor units are for muscles that do not require such fine control.The neuromuscular junction is made of an axon terminal and the portion of the muscle fiber sarcolemma it nearly touches (called the motor endplate). The neurotransmitter released at the neuromuscular junction in skeletal muscle is ACh. The motor endplate is rich in thousands of ACh receptors; the receptors are integral proteins containing binding sites for ACh and sodium channels. Nerve impulse (action potential) reaches the axon terminal, which triggers calcium influx into the axon terminal.Calcium influx causes synaptic vesicles to release ACh via exocytosis. ACh diffuses across synaptic cleft.ACh binds to theACh receptor on the sarcolemma. Succinylcholine, a drug used to induce paralysis during surgery, binds to ACh receptors more tightly than ACh. Succinylcholine initially causes some depolarization, but then itbinds to the receptor, preventing ACh from binding. Therefore, it blocks the muscles stimulation by ACh, causing paralysis. Another drug that acts in a similar fashion is curare. These drugs do not cause pain relief or unconsciousness; thus, they are combined with other drugs during surgery. When ACh binds the receptor, it opens chemically regulated ion channels, which are sodium channels through the receptor molecule. Sodium, which is in high concentration outside cells and in low concentration inside cells, rushes into the cell through the channels.The cell, whose resting membrane potential along the inside of the membrane is negative when comparedwith the outside of the membrane, becomes positively charged along the inside of the membrane when sodium (a positive ion) rushes in. This change from a negative charge to a positive charge along the inner membrane is termed depolarization. The depolarization of one region of the sarcolemma (the motor endplate) initiates an action potential, which is a propagating wave of depolarization that travels (propagates) along the sarcolemma. Regions of membrane that become depolarized rapidly restore their proper ionic concentrations along their inner and outer surfaces in a process termed repolarization. (This process of depolarization, propagation, and repolarization is similar to dominoes that topple each other but also spring back into the upright position shortly afterward.)The action potential also propagates along the membrane lining the T tubules entering the cell. This action potential traveling along the T tubules causes the sarcoplasmic reticulum to release calcium into sarcoplasm.Calcium binds with troponin, causing it to pull on tropomyosin to change its or ientation, exposing myosin-binding sites on actin. An ATPase, which also functions as a myosin cross-bridging protein, splits ATP into adenosine diphosphate (ADP) + phosphate (P) in the previous contraction cycle. This energizes the myosin head. The energized myosin head, or cross-bridge, combines with myosin-binding sites on actin. Power stroke occurs. The attachment of the energized cross-bridge triggers a pivoting motion (ie, power stroke) of the myosin head. During the power stroke, ADP and P are released from the myosin cross-bridge. The power stroke causes thin actinmyofilaments to slide past thick myosin myofilaments toward the center of the A bands.ATP attaches to the myosin head again, allowing it to detach from actin. (In rigor mortis, an ATP deficiency occurs. Cross-bridges remain, and the muscles are rigid.)ATP is broken down to ADP and P, which cocks the myosin head again, preparing it to perform another power stroke if needed. Repeated detachment and reattachment of the cross-bridges results in shortening without much increase in tension during the shortening phase (isotonic contraction) or results in increased tension without shortening (isometric contraction).Release of the enzyme acetylcholinesterasein the neuromuscular junction destroys ACh and stops the generation of a muscle action potential. Calcium is taken back up (resequestered) in the sarcoplasmic reticulum, and myosin cross-bridges separate. ATP is required to separate myosin-actin cross-bridges. The muscle fiber resumes its resting state. The chemical energy that fuels muscular activities is ATP. For the first 5 or 6 seconds of muscle power, muscular activity can depend on the ATP that is already present in the muscle cells. Beyond this time, new amounts of ATP must be formed to enable the activation of muscular contractions that are needed to support longer and more vigorous physical activities. For activities that require a quick burst of energy that cannot be supplied by the ATP present in the muscle cells, the next 10-15 seconds of muscle power can be provided through the bodys use of the phosphagen system, which uses a substance called creatine phosphate to recycle ADP into ATP.4 For longer and more intense periods of physical activity, the body must rely on systems that break down the sugars (glucose) to produce ATP. The complete breakdown of glucose occurs in 2 ways: through anaerobic respiration (does not use oxygen) and through aerobic respiration (occurs in the presence of oxygen). The anaerobic use of gluco se to form ATP occurs as the body increases its muscle use beyond the capability of the phosphagen system to supply energy. In particular, the glycogen lactic acid system, through its anaerobic breakdown of glucose, provides approximately 30-40 seconds more of maximal muscle activity. For this system, each glucose molecule is split into 2 pyruvic acid molecules, and energy is released to form several ATP molecules, providing the extra energy. Then, the pyruvic acid partially breaks down further to produce lactic acid. If the lactic acid is allowed to accumulate in the muscle, one experiences muscle fatigue. At this point, the aerobic system must activate.The aerobic system in the body is used for sports that require an extensive and enduring expenditure of energy, such as a marathon race. Endurance sports absolutely require aerobic energy. A large amount of ATP must be provided to muscles to sustain the muscle power needed to perform such events without an excessive production of la ctic acid. This can only be accomplished when oxygen in the body is used to break down the pyruvic acid (that was produced anaerobically) into carbon dioxide, water, and energy by way of a very complex series of reactions known as the citric acid cycle. This cycle supports muscle usage for as long as the nutrients in the body last. The breakdown of pyruvic acid requires oxygen and slows or eliminates the accumulation of lactic acid. In summary, the 3 different muscle metabolic systems that supply the energy required for various activities are as follows: Phosphagen system (for 10- to 15-sec bursts of energy)Glycogen lactic acid system (for another 30-40 sec of energy)Aerobic system (provides a great deal of energy that is only limited by the bodys ability to supply oxygen and other important nutrients) Many sports require the use of a combination of these metabolic systems. By considering the vigor of a sports activity and its duration, one can estimate very closely which of the ene rgy systems are used for each activity. During muscular exercise, blood vessels in muscles dilate and blood flow is increased in order to increase the available oxygen supply. Up to a point, the available oxygen is sufficient to meet the energy needs of the body. However, when muscular exertion is very great, oxygen cannot be supplied to muscle fibers fast enough, and the aerobic breakdown of pyruvic acid cannot produce all the ATP required for further muscle contraction. During such periods, additional ATP is generated by anaerobic glycolysis. In the process, most of the pyruvic acid produced is converted to lactic acid. Although approximately 80% of the lactic acid diffuses from the skeletal muscles and is transported to the liver for conversion back to glucose or glycogen, some lactic acid accumulates in muscle tissue, making muscle contraction painful and causing fatigue. Ultimately, once adequate oxygen is available, lactic acid must be catabolized completely into carbon dioxide and water. After exercise has stopped, extra oxygen is required to metabolize lactic acid; to replenish ATP, phosphocreatine, and glycogen; and to replace (pay back) any oxygen that has been borrowed from hemoglobin, myoglobin (an iron-containing substance similar to hemoglobin that is found in muscle fibers), air in the lungs, and body fluids. The additional oxygen that must be taken into the body after vigorous exercise to restore all systems to their normal states is called oxygen debt. The debt is paid back by labored breathing that continues after exercise has stopped. Thus, the accumulation of lactic acid causes hard breathing and sufficient discomfort to stop muscle activity until homeostasis is restored.5 Eventually, muscle glycogen must also be restored. Restoration of muscle glycogen is accomplished through diet and may take several days, depending on the intensity of exercise. The maximum rate of oxygen consumption during the aerobic catabolism of pyruvic acid is called maximal oxygen uptake. Maximal oxygen uptake is determined by sex (higher in males), age (highest at approximately age 20 y), and size (increases with body size). Highly trained athletes can have maximal oxygen uptakes that are twice that of average people, probably owing to a combination of genetics and training. As a result, highly trained athletes are capable of greater muscular activity without increasing their lactic acid production and have lower oxygen debts, which is why they do not become short of breath as readily as untrained individuals. The best examples of light exercise are walking and light jogging. The muscles that are recruited during this type of exercise are those that contain a large amount of type I muscle cells, and, because these cells have a good blood supply, it is easy for fuels and oxygen to travel to the muscle. ATP consumption makes ADP available for new ATP synthesis. The presence of ADP (and the resulting synthesis of ATP) simulates the movement of hydrogen (H+) into the mitochondria; this, in turn, reduces the proton gradient and thus stimulates electron transport. The hydrogen on the reduced form of nicotinamide adenine dinucleotide (NADH) is used up, nicotinamide adenine dinucleotide (NAD) becomes available, and fatty acids and glucose are oxidized. Incidentally, the calcium released during contraction stimulates the enzymes in the Krebs cycle and stimulates the movement of the glucose transporter 4 (GLUT-4) from inside of the muscle cell to the cell membrane. Both these exercise-induced respon ses augment the elevation in fuel oxidation caused by the increase in ATP consumption. An increase in the pace of running simply results in an increased rate of fuel consumption, an increased fatty acid release, and, therefore, an increase in the rate of muscle fatty acid oxidation. However, if the intensity of the exercise increases even further, a stage is reached in which the rate of fatty acid oxidation becomes limited. The reasons why the rate of fatty acid oxidation reaches a maximum are not clear, but it is possible that the enzymes in the beta-oxidation pathway are saturated (ie, they reach a stage in which their maximal velocity [Vmax] is less than the rate of acetyl-coenzyme A [acetyl-CoA] consumption in the Krebs cycle). Alternatively, it may be that the availability of carnitine (the chemical required to transport the fatty acids into the mitochondria) becomes limited. Whatever the reason, the consequence is that as the pace rises, the demand for acetyl-CoA cannot be met by fatty acid oxidation alone. The accumulation of acetyl-CoA that was so effective at inhibiting the oxidation of glucose is no longer present, so pyruvate dehydrogenase starts working again and pyruvate is converted into acetyl-CoA. In other words, more of the glucose that enters the muscle cell is oxidized fully to carbon dioxide. Therefore, the energy used during moderate exercise is derived from a mixture of fatty acid and glucose oxidation. As the intensity of the exercise increases even further (ie, running at the pace of middle-distance races), the rate at which the muscles can extract glucose from the blood becomes limited. In other words, the rate of glucose transport reaches Vmax, either because the blood cannot supply the glucose fast enough or the number of GLUT-4s becomes limited. ATP generation cannot be serviced completely by exogenous fuels, and ATP levels decrease. Not only does this stimulate phosphofructokinase, it also stimulates glycogen phosphorylase. This me ans that glycogen stored within the muscle cells is broken down to provide glucose. Therefore, the fuel mix during strenuous exercise is composed of contributions from blood-borne glucose and fatty acids and from endogenously stored glycogen.Being fit (biochemically speaking) means that the individual has a well-developed cardiovascular system that can efficiently supply nutrients and oxygen to the muscles. Fit people have muscle cells that are well perfused with capillaries (ie, they have a good muscle blood supply). Their muscle cells also have a large number of mitochondria, and those mitochondria have a high activity of Krebs cycle enzymes, electron transport carriers, and oxidation enzymes. Individuals who are unfit must endure the consequences of a poorer blood supply, fewer mitochondria, less electron transport units, a lower activity of the Krebs cycle, and poorer activity of beta-oxidation enzymes. To generate ATP in the mitochondria, a steady supply of fuel and oxygen and decent activity of the oxidizing enzymes and carriers are needed. If any of these components are lacking, the rate at which ATP can be produced by mitochondria is compromised. Under these circumstances, the production of ATP by aerobic means is not sufficient to provide the muscles with sufficient ATP to sustain contractions. The result is anaerobic ATP generation using glycolysis. Increasing the flux through glycolysis but not increasing the oxidative consumption of the resulting pyruvate increases the production of lactate. The purpose of respiration is to provide oxygen to the tissues and to remove carbon dioxide from the tissues. To accomplish this, 4 major events must be regulated, as follows: Pulmonary ventilation. Diffusion of oxygen and carbon dioxide between the alveoli and the blood, Transport of oxygen and carbon dioxide in the blood and body fluids and to and from the cells, Regulation of ventilation and other aspects of respiration: Exercise causes these factors to change, but the body is designed to maintain homeostasisWhen one goes from a state of rest to a state of maximal intensity of exercise, oxygen consumption, carbon dioxide formation, and total pulmonary and alveolar ventilation increase by approximately 20-fold. A linear relationship exists between oxygen consumption and ventilation. At maximal exercise, pulmonary ventilation is 100-110 L/min, whereas maximal breathing capacity is 150-170 L/min. Thus, the maximal breathing capacity is approximately 50% greater than the actual pulmon ary ventilation during maximal exercise. This extra ventilation provides an element of safety that can be called on if the situation demands it (eg, at high altitudes, under hot conditions, abnormality in the respiratory system). Therefore, the respiratory system itself is not usually the most limiting factor in the delivery of oxygen to the muscles during maximal muscle aerobic metabolism. VO2 max is the rate of oxygen consumption under maximal aerobic metabolism. This rate in short-term studies is found to increase only 10% with the effect of training. However, that of a person who runs in marathons is 45% greater than that of an untrained person. This is believed to be partly genetically determined (eg, stronger respiratory muscles, larger chest size in relation to body size) and partly due to long-term training. Oxygen diffusing capacity is a measure of the rate at which oxygen can diffuse from the alveoli into the blood. An increase in diffusing capacity is observed in a state of maximal exercise. This results from the fact that blood flow through many of the pulmonary capillaries is sluggish in the resting state. In exercise, increased blood flow through the lungs causes all of the pulmonary capillaries to be perfused at their maximal level, providing a greater surface area through which oxygen can diffuse into the pulmonary capillary blood. Athletes who require greater amounts of oxygen per minute have been found to have higher diffusing capacities, but the exact reason why is not yet known. Although one would expect the oxygen pressure of arterial blood to decrease during strenuous exercise and carbon dioxide pressure of venous blood to increase far above normal, this is not the case. Both of these values remain close to normal. Stimulatory impulses from higher centers of the brain and from joint and muscle proprioceptive stimulatory reflexes account for the nervous stimulation of the respiratory and vasomotor center that provides almost exactly the pr oper increase in pulmonary ventilation to keep the blood respiratory gases almost normal. If nervous signals are too strong or weak, chemical factors bring about the final adjustment in respiration that is required to maintain homeostasis. Regular exercise makes the cardiovascular system more efficient at pumping blood and delivering oxygen to the exercise muscles. Releases of adrenaline and lactic acid into the blood result in an increase of the heart rate (HR). Basic definitions of terms are as follows:VO2 equals cardiac output times oxygen uptake necessary to supply oxygen to muscles. The Fick equation is the basis for determination of VO2. Exercises increase some of the different components of the cardiovascular system, such as stroke volume (SV), cardiac output, systolic blood pressure (BP), and mean arterial pressure. A greater percentage of the cardiac output goes to the exercising muscles. At rest, muscles receive approximately 20% of the total blood flow, but during exercise, the blood flow to muscles increases to 80-85%. To meet the metabolic demands of skeletal muscle during exercise, 2 major adjustments to blood flow must occur. First, cardiac output from the heart must increase. Second, blood flow from ina ctive organs and tissues must be redistributed to active skeletal muscle. Generally, the longer the duration of exercise, the greater the role the cardiovascular system plays in metabolism and performance during the exercise bout. An example would be the 100-meter sprint (little or no cardiovascular involvement) versus a marathon (maximal cardiovascular involvement). The cardiovascular system helps transport oxygen and nutrients to tissues, transport carbon dioxide and other metabolites to the lungs and kidneys, and distribute hormones throughout the body. The cardiovascular system also assists with thermoregulation.The pumping of blood by the heart requires the following 2 mechanisms to be efficient:Alternate periods of relaxation and contraction of the atria and ventriclesCoordinated opening and closing of the heart valves for unidirectional flow of blood The cardiac cycle is divided into 2 phases: ventricular diastole and ventricular systole.This phase begins with the opening of the atrioventricular (AV) valves. The mitral valve (located between the left atrium and left ventricle) opens when the left ventricular pressure falls below the left atrial pressure, and the blood from left atrium enters the left ventricle.Later, as the blood continues to flow into the left ventricle, the pressure in both chambers tends to equalize.At the end of the di astole, left atrial contractions cause an increase in left atrial pressure, thus again creating a pressure gradient between the left atrium and ventricle and forcing blood into the left ventricle.Ventricular systole begins with the contraction of the left ventricle, which is caused by the spread of an action potential over the left ventricle. The contraction of the left ventricle causes an increase in the left ventricular pressure. When this pressure is higher than the left atrial pressure, the mitral valve is closed abruptly.The left ventricular pressure continues to rise after the mitral valve is closed. When the left ventricular pressure rises above the pressure in the aorta, the aortic valve opens. This period between the closure of the mitral valve and the opening of the aortic valve is called isovolumetric contraction phase.The blood ejects out of the left ventricle and into the aorta once the aortic valve is opened. As the left ventricular contraction is continued, 2 processe s lead to a fall in the left ventricular pressure. These include a decrease in the strength of the ventricular contraction and a decrease in the volume of blood in the ventricle.When the left ventricular pressure falls below the aortic pressure, the aortic valve is closed. After the closure of the aortic valve, the left ventricular pressure falls rapidly as the left ventricle relaxes. When this pressure falls below the left atrial pressure, the mitral valve opens and allows blood to enter left ventricle. The period between the closure of the aortic valve closure and the opening of the mitral valve is called isovolumetric relaxation time. Right-sided heart chambers undergo the same phases simultaneously. Most of the work of the heart is completed when ventricular pressure exists. The greater the ventricular pressure, the greater the workload of the heart. Increases in BP dramatically increase the workload of the heart, and this is why hypertension is so harmful to the heart.Arterial BP is the pressure that is exerted against the walls of the vascular system. BP is determined by cardiac output and peripheral resistance. Arterial pressure can be estimated using a sphygmomanometer and a stethoscope. The reference range for males is 120/80 mm Hg; the reference range for females is 110/70 mm Hg. The difference between systolic and diastolic pressure is called the pulse pressure. The average pressure during a cardiac cycle is called the mean arterial pressure (MAP). MAP determines the rate of blood flow through the systemic circulation.During rest, MAP = diastolic BP + (0.33 X pulse pressure). For example, MAP = 80 + (0.33 X [120-80]), MAP = 93 mm Hg. During exercise, MAP = diastolic BP + (0.50 X pulse pressure). For example, MAP = 80 + (0.50 X [160-80]), MAP = 120 mm Hg. The heart has the ability to generate its own electrical activity, which is known as intrinsic rhythm. In the healthy heart, contraction is initiated in the sinoatrial (SA) node, which is often called the hearts pacemaker. If the SA node cannot set the rate, then other tissues in the heart are able to generate an electrical potential and establish the HR.The parasympathetic nervous system and the sympathetic nervous system affect a personsHR. Parasympathetic nervous system: The vagus nerve originates in the medulla and innervates the SA and AV nodes. The nerve releases ACh as the neurotransmitter. The response is a decrease in SA node and AV node activity, which causes a decrease in HR. Sympathetic nervous system: The nerves arise from the spinal cord and innervate the SA node and ventricular muscle mass. The nerves release norepinephrine as the neurotransmitter. The response is an increase in HR and a force of contraction of the ventricles.At rest, sympathetic and parasympathetic ne rvous stimulation are in balance. During exercise, parasympathetic stimulation decreases and sympathetic stimulation increases. Several factors can alter sympathetic nervous system input.Baroreceptors are groups of neurons located in the carotid arteries, the arch of aorta, and the right atrium. These neurons sense changes in pressure in the vascular system. An increase in BP results in an increase in parasympathetic activity except during exercise, when the sympathetic activity overrides the parasympathetic activity. Chemoreceptors are groups of neurons located in the arch of the aorta and the carotid arteries. These neurons sense changes in oxygen concentration. When oxygen concentration in the blood is decreased, parasympathetic activity decreasesand sympathetic activity increases. Temperature receptors are neurons located throughout the body. These neurons are sensitive to changes in body temperature. As temperature increases, sympathetic activity increases to cool Effects of Exercise on the Human Body Effects of Exercise on the Human Body Exercise represents one the highest levels of extreme stresses to which the body can be exposed. Exercise physiology is the study of the function of the human body during various acute and chronic exercise conditions. These effects are significant during both short, high intensity exercise as well as with prolonged strenuous exercise such as done in endurance sports like marathons, ultramarathons, and road bicycle racing. In exercise, the liver generates extra glucose, while increased cardiovascular activity by the heart, and respiration by the lungs, provides an increased supply of oxygen. When exercise is very prolonged and strenuous, a decline, however, can occur in blood levels of glucose. In some individuals, this might even cause hypoglycemia and hypoxemia. There can also be cognitive and physical impairments due to dehydration. Another risk is low plasma sodium blood levels. Prolonged exercise is made possible by the human thermoregulation capacity to remove exercise waste hea t by sweat evaporation. This capacity evolved to enable early humans after many hours of persistence hunting to exhaust game animals that cannot remove so effectively exercise heat from their body. In general, the exercise-related measurements established for women follow the same general principles as those established for men, except for the quantitative differences caused by differences in body size, body composition, and levels of testosterone. In women, the values of muscle strength, pulmonary ventilation, and cardiac output (all variables related with muscle mass) are generally 60-75% of the exercise physiology values recorded in men. When measured in terms of strength per square centimeter, the female muscle can achieve the same force of contraction as that of a male. The functions of muscle tissues assume roles in homeostasis, as follows: Excitability Property of receiving and responding to stimuli such as the following: Neurotransmitters: Acetylcholine (ACh) stimulates skeletal muscle to contract, electrical stimuli: Applying electrical stimuli between cardiac and smooth muscle cells causes the muscles to contract, Applying a shock to skeletal muscle causes contraction, Hormonal stimuli: Oxytocin stimulates smooth muscle in the uterus to contract during labor.Contractility Ability to shorten. Extensibility Ability to stretch without damageElasticity Ability to return to original shape after extensionThrough contraction, muscle provides motion of the body (skeletal muscle), motion of blood (cardiac muscle), and motion of hollow organs such as the uterus, esophagus, stomach, intestines, and bladder (smooth muscle).Muscle tissue also helps maintain posture and produce heat. A large amount of body heat is produced by metabolism and by muscle con traction. Muscle contraction during shivering warms the body. Skeletal muscle consists of fibers (cells). These cells are up to 100 Â µm in diameter and often are as long as the muscle. Each contains sarcoplasm (cytoplasm) and multiple peripheral nuclei per fiber. Skeletal muscle is actually formed by the fusion of hundreds of embryonic cells. Other cell structures include the following:Each fiber is covered by a sarcolemma (plasma membrane). The sarcoplasmic reticulum (smooth endoplasmic reticulum) stores calcium, which is released into the sarcoplasm during muscle contraction. Transverse tubules (T tubules), which are extensions of the sarcolemma that penetrate cells, transmit electrical impulses from the sarcolemma inward, so electrical impulses penetrate deeply into the cell. Besides conducting electricity along their walls, T tubules contain extracellular fluid rich in glucose and oxygen.The sarcoplasm of fiber is rich in glycogen (glucose polymer) granules and myoglobin (oxygen-storing protein). It also is rich in mitochondria. Each fibe r contains hundreds to thousands of rodlike myofibrils, which are bundles of thin and thick protein chains termed myofilaments. From a cross-sectional view of a myofibril, each thick filament is surrounded by a hexagonal array of 6 thin filaments. Each thin filament is surrounded by a triangular array of thick filaments.myofilaments are composed of 3 proteins: actin, tropomyosin, and troponin. Thick myofilaments consist of bundles of approximately 200 myosin molecules. Myosin molecules look like double-headed golf clubs (both heads at the same end). The heads of the golf clubs are called myosin heads; they are also called cross-bridges because they link thick and thin filaments during contraction. They contain actin andadenosine triphosphate (ATP) binding sites. Myosin heads project out from the thick filaments, allowing them to bind to the thin filaments during contraction. Actin is a long chain of multiple globular proteins, similar in shape to kidney beans. Each globular subunit contains a myosin-binding site. Tropomyosin is a long strand of protein that covers the myosin-binding sites on actin when the muscle is relaxed. Troponin is a polypeptide complex that binds to tropomyosin, helping to position it over the myosin-binding sites on actin. During muscle contraction, calcium binds troponin, which causes tropomyosin to roll off of the myosin binding sites on actin. A muscle action potential travels over sarcolemma and enters the T tubules, causing the sarcoplasmic reticulum to release calcium into the sarcoplasm. This triggers the contractile process.Myosin cross-bridges pull on the actin myofilaments, causing the thin myofilaments of a sarcomere to slide toward the centers of the H zones.Deep fascia is a broad band of dense irregular connective tissue beneath and around muscle and organs. Deep fascia is different from superficial fascia, which is loose areolar connective tissue.Other connective-tissue components (all are extensions of deep fascia) include epimysium, which covers the entire muscle; perimysium, which penetrates into muscle and surrounds bundles of fibers called fascicles; and endomysium, which is delicate, barely visible, loose areolar tissue covering individual fibers (ie, individual cells).Tendons and aponeuroses are tough extensions of epimysium, perimysium, and endomysium. Tendons and aponeuroses are made of dense regular co nnective tissue and attach the muscle to bone or other muscle. Aponeuroses are broad, flat tendons. Tendon sheaths contain synovial fluid and enclose certain tendons. Tendon sheaths allow tendons to slide back and forth next to each other with lower friction. Tenosynovitis is inflammation of the tendon sheaths and tendons, especially those of the wrists, shoulders, and elbows. Tendons are not contractile and not very stretchy; furthermore, they are not very vascular and they heal poorly. Nerves convey impulses for muscular contraction. Nerves are bundles of nerve cell processes. Each nerve cell process (ie, axon) divides at its tip into a few to 10,000 branches called telodendria. At the end of each of these branches is an axon terminal that is rich in neurotransmitters.Blood provides nutrients and oxygen for contraction. An artery and a vein usually accompany a nerve that penetrates skeletal muscle. Arteries in muscles dilate during active muscular activity, thus increasing the supply of oxygen and glucose.A motor nerve is a bundle of axons that conducts nerve impulses away from the brain or spinal cord toward muscles. Each axon transmits an action potential (ie, nerve impulse), which is a burst of electricity. The nerve impulse travels along the axons at a steady rate, like fire travels along a fuse; however, nerve impulses travel extremely fast. Each axon has 4-2000 or more branches (ie, telodendria), with an average of 150 telodendria. Each separate branch suppli es a separate muscle cell. Thus, if an axon has 10 branches, it supplies 10 muscle fibers. Small motor units are for fine control of muscles; large motor units are for muscles that do not require such fine control.The neuromuscular junction is made of an axon terminal and the portion of the muscle fiber sarcolemma it nearly touches (called the motor endplate). The neurotransmitter released at the neuromuscular junction in skeletal muscle is ACh. The motor endplate is rich in thousands of ACh receptors; the receptors are integral proteins containing binding sites for ACh and sodium channels. Nerve impulse (action potential) reaches the axon terminal, which triggers calcium influx into the axon terminal.Calcium influx causes synaptic vesicles to release ACh via exocytosis. ACh diffuses across synaptic cleft.ACh binds to theACh receptor on the sarcolemma. Succinylcholine, a drug used to induce paralysis during surgery, binds to ACh receptors more tightly than ACh. Succinylcholine initially causes some depolarization, but then itbinds to the receptor, preventing ACh from binding. Therefore, it blocks the muscles stimulation by ACh, causing paralysis. Another drug that acts in a similar fashion is curare. These drugs do not cause pain relief or unconsciousness; thus, they are combined with other drugs during surgery. When ACh binds the receptor, it opens chemically regulated ion channels, which are sodium channels through the receptor molecule. Sodium, which is in high concentration outside cells and in low concentration inside cells, rushes into the cell through the channels.The cell, whose resting membrane potential along the inside of the membrane is negative when comparedwith the outside of the membrane, becomes positively charged along the inside of the membrane when sodium (a positive ion) rushes in. This change from a negative charge to a positive charge along the inner membrane is termed depolarization. The depolarization of one region of the sarcolemma (the motor endplate) initiates an action potential, which is a propagating wave of depolarization that travels (propagates) along the sarcolemma. Regions of membrane that become depolarized rapidly restore their proper ionic concentrations along their inner and outer surfaces in a process termed repolarization. (This process of depolarization, propagation, and repolarization is similar to dominoes that topple each other but also spring back into the upright position shortly afterward.)The action potential also propagates along the membrane lining the T tubules entering the cell. This action potential traveling along the T tubules causes the sarcoplasmic reticulum to release calcium into sarcoplasm.Calcium binds with troponin, causing it to pull on tropomyosin to change its or ientation, exposing myosin-binding sites on actin. An ATPase, which also functions as a myosin cross-bridging protein, splits ATP into adenosine diphosphate (ADP) + phosphate (P) in the previous contraction cycle. This energizes the myosin head. The energized myosin head, or cross-bridge, combines with myosin-binding sites on actin. Power stroke occurs. The attachment of the energized cross-bridge triggers a pivoting motion (ie, power stroke) of the myosin head. During the power stroke, ADP and P are released from the myosin cross-bridge. The power stroke causes thin actinmyofilaments to slide past thick myosin myofilaments toward the center of the A bands.ATP attaches to the myosin head again, allowing it to detach from actin. (In rigor mortis, an ATP deficiency occurs. Cross-bridges remain, and the muscles are rigid.)ATP is broken down to ADP and P, which cocks the myosin head again, preparing it to perform another power stroke if needed. Repeated detachment and reattachment of the cross-bridges results in shortening without much increase in tension during the shortening phase (isotonic contraction) or results in increased tension without shortening (isometric contraction).Release of the enzyme acetylcholinesterasein the neuromuscular junction destroys ACh and stops the generation of a muscle action potential. Calcium is taken back up (resequestered) in the sarcoplasmic reticulum, and myosin cross-bridges separate. ATP is required to separate myosin-actin cross-bridges. The muscle fiber resumes its resting state. The chemical energy that fuels muscular activities is ATP. For the first 5 or 6 seconds of muscle power, muscular activity can depend on the ATP that is already present in the muscle cells. Beyond this time, new amounts of ATP must be formed to enable the activation of muscular contractions that are needed to support longer and more vigorous physical activities. For activities that require a quick burst of energy that cannot be supplied by the ATP present in the muscle cells, the next 10-15 seconds of muscle power can be provided through the bodys use of the phosphagen system, which uses a substance called creatine phosphate to recycle ADP into ATP.4 For longer and more intense periods of physical activity, the body must rely on systems that break down the sugars (glucose) to produce ATP. The complete breakdown of glucose occurs in 2 ways: through anaerobic respiration (does not use oxygen) and through aerobic respiration (occurs in the presence of oxygen). The anaerobic use of gluco se to form ATP occurs as the body increases its muscle use beyond the capability of the phosphagen system to supply energy. In particular, the glycogen lactic acid system, through its anaerobic breakdown of glucose, provides approximately 30-40 seconds more of maximal muscle activity. For this system, each glucose molecule is split into 2 pyruvic acid molecules, and energy is released to form several ATP molecules, providing the extra energy. Then, the pyruvic acid partially breaks down further to produce lactic acid. If the lactic acid is allowed to accumulate in the muscle, one experiences muscle fatigue. At this point, the aerobic system must activate.The aerobic system in the body is used for sports that require an extensive and enduring expenditure of energy, such as a marathon race. Endurance sports absolutely require aerobic energy. A large amount of ATP must be provided to muscles to sustain the muscle power needed to perform such events without an excessive production of la ctic acid. This can only be accomplished when oxygen in the body is used to break down the pyruvic acid (that was produced anaerobically) into carbon dioxide, water, and energy by way of a very complex series of reactions known as the citric acid cycle. This cycle supports muscle usage for as long as the nutrients in the body last. The breakdown of pyruvic acid requires oxygen and slows or eliminates the accumulation of lactic acid. In summary, the 3 different muscle metabolic systems that supply the energy required for various activities are as follows: Phosphagen system (for 10- to 15-sec bursts of energy)Glycogen lactic acid system (for another 30-40 sec of energy)Aerobic system (provides a great deal of energy that is only limited by the bodys ability to supply oxygen and other important nutrients) Many sports require the use of a combination of these metabolic systems. By considering the vigor of a sports activity and its duration, one can estimate very closely which of the ene rgy systems are used for each activity. During muscular exercise, blood vessels in muscles dilate and blood flow is increased in order to increase the available oxygen supply. Up to a point, the available oxygen is sufficient to meet the energy needs of the body. However, when muscular exertion is very great, oxygen cannot be supplied to muscle fibers fast enough, and the aerobic breakdown of pyruvic acid cannot produce all the ATP required for further muscle contraction. During such periods, additional ATP is generated by anaerobic glycolysis. In the process, most of the pyruvic acid produced is converted to lactic acid. Although approximately 80% of the lactic acid diffuses from the skeletal muscles and is transported to the liver for conversion back to glucose or glycogen, some lactic acid accumulates in muscle tissue, making muscle contraction painful and causing fatigue. Ultimately, once adequate oxygen is available, lactic acid must be catabolized completely into carbon dioxide and water. After exercise has stopped, extra oxygen is required to metabolize lactic acid; to replenish ATP, phosphocreatine, and glycogen; and to replace (pay back) any oxygen that has been borrowed from hemoglobin, myoglobin (an iron-containing substance similar to hemoglobin that is found in muscle fibers), air in the lungs, and body fluids. The additional oxygen that must be taken into the body after vigorous exercise to restore all systems to their normal states is called oxygen debt. The debt is paid back by labored breathing that continues after exercise has stopped. Thus, the accumulation of lactic acid causes hard breathing and sufficient discomfort to stop muscle activity until homeostasis is restored.5 Eventually, muscle glycogen must also be restored. Restoration of muscle glycogen is accomplished through diet and may take several days, depending on the intensity of exercise. The maximum rate of oxygen consumption during the aerobic catabolism of pyruvic acid is called maximal oxygen uptake. Maximal oxygen uptake is determined by sex (higher in males), age (highest at approximately age 20 y), and size (increases with body size). Highly trained athletes can have maximal oxygen uptakes that are twice that of average people, probably owing to a combination of genetics and training. As a result, highly trained athletes are capable of greater muscular activity without increasing their lactic acid production and have lower oxygen debts, which is why they do not become short of breath as readily as untrained individuals. The best examples of light exercise are walking and light jogging. The muscles that are recruited during this type of exercise are those that contain a large amount of type I muscle cells, and, because these cells have a good blood supply, it is easy for fuels and oxygen to travel to the muscle. ATP consumption makes ADP available for new ATP synthesis. The presence of ADP (and the resulting synthesis of ATP) simulates the movement of hydrogen (H+) into the mitochondria; this, in turn, reduces the proton gradient and thus stimulates electron transport. The hydrogen on the reduced form of nicotinamide adenine dinucleotide (NADH) is used up, nicotinamide adenine dinucleotide (NAD) becomes available, and fatty acids and glucose are oxidized. Incidentally, the calcium released during contraction stimulates the enzymes in the Krebs cycle and stimulates the movement of the glucose transporter 4 (GLUT-4) from inside of the muscle cell to the cell membrane. Both these exercise-induced respon ses augment the elevation in fuel oxidation caused by the increase in ATP consumption. An increase in the pace of running simply results in an increased rate of fuel consumption, an increased fatty acid release, and, therefore, an increase in the rate of muscle fatty acid oxidation. However, if the intensity of the exercise increases even further, a stage is reached in which the rate of fatty acid oxidation becomes limited. The reasons why the rate of fatty acid oxidation reaches a maximum are not clear, but it is possible that the enzymes in the beta-oxidation pathway are saturated (ie, they reach a stage in which their maximal velocity [Vmax] is less than the rate of acetyl-coenzyme A [acetyl-CoA] consumption in the Krebs cycle). Alternatively, it may be that the availability of carnitine (the chemical required to transport the fatty acids into the mitochondria) becomes limited. Whatever the reason, the consequence is that as the pace rises, the demand for acetyl-CoA cannot be met by fatty acid oxidation alone. The accumulation of acetyl-CoA that was so effective at inhibiting the oxidation of glucose is no longer present, so pyruvate dehydrogenase starts working again and pyruvate is converted into acetyl-CoA. In other words, more of the glucose that enters the muscle cell is oxidized fully to carbon dioxide. Therefore, the energy used during moderate exercise is derived from a mixture of fatty acid and glucose oxidation. As the intensity of the exercise increases even further (ie, running at the pace of middle-distance races), the rate at which the muscles can extract glucose from the blood becomes limited. In other words, the rate of glucose transport reaches Vmax, either because the blood cannot supply the glucose fast enough or the number of GLUT-4s becomes limited. ATP generation cannot be serviced completely by exogenous fuels, and ATP levels decrease. Not only does this stimulate phosphofructokinase, it also stimulates glycogen phosphorylase. This me ans that glycogen stored within the muscle cells is broken down to provide glucose. Therefore, the fuel mix during strenuous exercise is composed of contributions from blood-borne glucose and fatty acids and from endogenously stored glycogen.Being fit (biochemically speaking) means that the individual has a well-developed cardiovascular system that can efficiently supply nutrients and oxygen to the muscles. Fit people have muscle cells that are well perfused with capillaries (ie, they have a good muscle blood supply). Their muscle cells also have a large number of mitochondria, and those mitochondria have a high activity of Krebs cycle enzymes, electron transport carriers, and oxidation enzymes. Individuals who are unfit must endure the consequences of a poorer blood supply, fewer mitochondria, less electron transport units, a lower activity of the Krebs cycle, and poorer activity of beta-oxidation enzymes. To generate ATP in the mitochondria, a steady supply of fuel and oxygen and decent activity of the oxidizing enzymes and carriers are needed. If any of these components are lacking, the rate at which ATP can be produced by mitochondria is compromised. Under these circumstances, the production of ATP by aerobic means is not sufficient to provide the muscles with sufficient ATP to sustain contractions. The result is anaerobic ATP generation using glycolysis. Increasing the flux through glycolysis but not increasing the oxidative consumption of the resulting pyruvate increases the production of lactate. The purpose of respiration is to provide oxygen to the tissues and to remove carbon dioxide from the tissues. To accomplish this, 4 major events must be regulated, as follows: Pulmonary ventilation. Diffusion of oxygen and carbon dioxide between the alveoli and the blood, Transport of oxygen and carbon dioxide in the blood and body fluids and to and from the cells, Regulation of ventilation and other aspects of respiration: Exercise causes these factors to change, but the body is designed to maintain homeostasisWhen one goes from a state of rest to a state of maximal intensity of exercise, oxygen consumption, carbon dioxide formation, and total pulmonary and alveolar ventilation increase by approximately 20-fold. A linear relationship exists between oxygen consumption and ventilation. At maximal exercise, pulmonary ventilation is 100-110 L/min, whereas maximal breathing capacity is 150-170 L/min. Thus, the maximal breathing capacity is approximately 50% greater than the actual pulmon ary ventilation during maximal exercise. This extra ventilation provides an element of safety that can be called on if the situation demands it (eg, at high altitudes, under hot conditions, abnormality in the respiratory system). Therefore, the respiratory system itself is not usually the most limiting factor in the delivery of oxygen to the muscles during maximal muscle aerobic metabolism. VO2 max is the rate of oxygen consumption under maximal aerobic metabolism. This rate in short-term studies is found to increase only 10% with the effect of training. However, that of a person who runs in marathons is 45% greater than that of an untrained person. This is believed to be partly genetically determined (eg, stronger respiratory muscles, larger chest size in relation to body size) and partly due to long-term training. Oxygen diffusing capacity is a measure of the rate at which oxygen can diffuse from the alveoli into the blood. An increase in diffusing capacity is observed in a state of maximal exercise. This results from the fact that blood flow through many of the pulmonary capillaries is sluggish in the resting state. In exercise, increased blood flow through the lungs causes all of the pulmonary capillaries to be perfused at their maximal level, providing a greater surface area through which oxygen can diffuse into the pulmonary capillary blood. Athletes who require greater amounts of oxygen per minute have been found to have higher diffusing capacities, but the exact reason why is not yet known. Although one would expect the oxygen pressure of arterial blood to decrease during strenuous exercise and carbon dioxide pressure of venous blood to increase far above normal, this is not the case. Both of these values remain close to normal. Stimulatory impulses from higher centers of the brain and from joint and muscle proprioceptive stimulatory reflexes account for the nervous stimulation of the respiratory and vasomotor center that provides almost exactly the pr oper increase in pulmonary ventilation to keep the blood respiratory gases almost normal. If nervous signals are too strong or weak, chemical factors bring about the final adjustment in respiration that is required to maintain homeostasis. Regular exercise makes the cardiovascular system more efficient at pumping blood and delivering oxygen to the exercise muscles. Releases of adrenaline and lactic acid into the blood result in an increase of the heart rate (HR). Basic definitions of terms are as follows:VO2 equals cardiac output times oxygen uptake necessary to supply oxygen to muscles. The Fick equation is the basis for determination of VO2. Exercises increase some of the different components of the cardiovascular system, such as stroke volume (SV), cardiac output, systolic blood pressure (BP), and mean arterial pressure. A greater percentage of the cardiac output goes to the exercising muscles. At rest, muscles receive approximately 20% of the total blood flow, but during exercise, the blood flow to muscles increases to 80-85%. To meet the metabolic demands of skeletal muscle during exercise, 2 major adjustments to blood flow must occur. First, cardiac output from the heart must increase. Second, blood flow from ina ctive organs and tissues must be redistributed to active skeletal muscle. Generally, the longer the duration of exercise, the greater the role the cardiovascular system plays in metabolism and performance during the exercise bout. An example would be the 100-meter sprint (little or no cardiovascular involvement) versus a marathon (maximal cardiovascular involvement). The cardiovascular system helps transport oxygen and nutrients to tissues, transport carbon dioxide and other metabolites to the lungs and kidneys, and distribute hormones throughout the body. The cardiovascular system also assists with thermoregulation.The pumping of blood by the heart requires the following 2 mechanisms to be efficient:Alternate periods of relaxation and contraction of the atria and ventriclesCoordinated opening and closing of the heart valves for unidirectional flow of blood The cardiac cycle is divided into 2 phases: ventricular diastole and ventricular systole.This phase begins with the opening of the atrioventricular (AV) valves. The mitral valve (located between the left atrium and left ventricle) opens when the left ventricular pressure falls below the left atrial pressure, and the blood from left atrium enters the left ventricle.Later, as the blood continues to flow into the left ventricle, the pressure in both chambers tends to equalize.At the end of the di astole, left atrial contractions cause an increase in left atrial pressure, thus again creating a pressure gradient between the left atrium and ventricle and forcing blood into the left ventricle.Ventricular systole begins with the contraction of the left ventricle, which is caused by the spread of an action potential over the left ventricle. The contraction of the left ventricle causes an increase in the left ventricular pressure. When this pressure is higher than the left atrial pressure, the mitral valve is closed abruptly.The left ventricular pressure continues to rise after the mitral valve is closed. When the left ventricular pressure rises above the pressure in the aorta, the aortic valve opens. This period between the closure of the mitral valve and the opening of the aortic valve is called isovolumetric contraction phase.The blood ejects out of the left ventricle and into the aorta once the aortic valve is opened. As the left ventricular contraction is continued, 2 processe s lead to a fall in the left ventricular pressure. These include a decrease in the strength of the ventricular contraction and a decrease in the volume of blood in the ventricle.When the left ventricular pressure falls below the aortic pressure, the aortic valve is closed. After the closure of the aortic valve, the left ventricular pressure falls rapidly as the left ventricle relaxes. When this pressure falls below the left atrial pressure, the mitral valve opens and allows blood to enter left ventricle. The period between the closure of the aortic valve closure and the opening of the mitral valve is called isovolumetric relaxation time. Right-sided heart chambers undergo the same phases simultaneously. Most of the work of the heart is completed when ventricular pressure exists. The greater the ventricular pressure, the greater the workload of the heart. Increases in BP dramatically increase the workload of the heart, and this is why hypertension is so harmful to the heart.Arterial BP is the pressure that is exerted against the walls of the vascular system. BP is determined by cardiac output and peripheral resistance. Arterial pressure can be estimated using a sphygmomanometer and a stethoscope. The reference range for males is 120/80 mm Hg; the reference range for females is 110/70 mm Hg. The difference between systolic and diastolic pressure is called the pulse pressure. The average pressure during a cardiac cycle is called the mean arterial pressure (MAP). MAP determines the rate of blood flow through the systemic circulation.During rest, MAP = diastolic BP + (0.33 X pulse pressure). For example, MAP = 80 + (0.33 X [120-80]), MAP = 93 mm Hg. During exercise, MAP = diastolic BP + (0.50 X pulse pressure). For example, MAP = 80 + (0.50 X [160-80]), MAP = 120 mm Hg. The heart has the ability to generate its own electrical activity, which is known as intrinsic rhythm. In the healthy heart, contraction is initiated in the sinoatrial (SA) node, which is often called the hearts pacemaker. If the SA node cannot set the rate, then other tissues in the heart are able to generate an electrical potential and establish the HR.The parasympathetic nervous system and the sympathetic nervous system affect a personsHR. Parasympathetic nervous system: The vagus nerve originates in the medulla and innervates the SA and AV nodes. The nerve releases ACh as the neurotransmitter. The response is a decrease in SA node and AV node activity, which causes a decrease in HR. Sympathetic nervous system: The nerves arise from the spinal cord and innervate the SA node and ventricular muscle mass. The nerves release norepinephrine as the neurotransmitter. The response is an increase in HR and a force of contraction of the ventricles.At rest, sympathetic and parasympathetic ne rvous stimulation are in balance. During exercise, parasympathetic stimulation decreases and sympathetic stimulation increases. Several factors can alter sympathetic nervous system input.Baroreceptors are groups of neurons located in the carotid arteries, the arch of aorta, and the right atrium. These neurons sense changes in pressure in the vascular system. An increase in BP results in an increase in parasympathetic activity except during exercise, when the sympathetic activity overrides the parasympathetic activity. Chemoreceptors are groups of neurons located in the arch of the aorta and the carotid arteries. These neurons sense changes in oxygen concentration. When oxygen concentration in the blood is decreased, parasympathetic activity decreasesand sympathetic activity increases. Temperature receptors are neurons located throughout the body. These neurons are sensitive to changes in body temperature. As temperature increases, sympathetic activity increases to cool