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

Nonprofit organizations Essay

TASC which stands for treatment alternative for safe communities is nonprofit making organization providing access to recovery and specialized services for people involved in corrections, criminal justice, public aid systems and child welfare. TASCS programs serve more than 30,000 people each year across Illinois every year including transitional programs for providing management for clinical case to over 4,000 adults each year who enter the community after incarceration. TASC work together with other service providers and partners to offer treatment, support recovery and establish faith –based organization. Addiction treatment field has grown in the past three decades due to expansion of market for illicit drugs in United States which started in 1960s and need for treatment services and intervention. In the areas of societal changes, key leaders have provided guidance on development in the last thirty years. They have shown their understanding on the need and possibilities for the field, they assess environmental landscape in order to anticipate the coming trends, take care of appropriate risks, act collectively in advancing the field and use influence and power in achieving a common vision. New leaders have been developed who are involved in identification and possible growth of individual who will be leaders of the field of alcohol, prevention and treatment of drugs in the years to come. Beyond leadership being understood as competencies and individual skills, cultures need to be developed about leadership at all levels in the organization. Leadership is involved in working together with others to advance the overall field. It explores, define and implement strategies to bring together diverse entities under common purposes and goals. There is a framework for developing leaders by convening efforts such as initiative for partners’ recovery. the main goals of efforts that are made in development of leadership is to make sure there is continuing evolution in leadership and having sound public policy and quality services to everyone. Fragmentation of philosophies has marked the field of preventing substance abuse and treatment of addiction for more than one century. Right now views are different concerning standardizing treatment methods, using medication-assisted treatment, purpose of recovery movement and outcome measures. Instead of a unified voice being presented, the field is described as multiple movements with many leaders and institutions having different agendas. Recently, the field is coming together with common philosophies to understand the science of recovery from addiction. Leadership understands societal context where the field is located. Plan for future of addiction treatment begin by assessing current environment and anticipating forces and trends for shaping the years to come. Forces in the society are external to control of the field yet for the people who will be involved in treatment and recovery; their future will be shaped by the people within the field by understanding opportunities and challenges that may emerge. The skills for a leader in treating addiction are complex. They need understanding of clinical and all service aspects and have business skills such as property acquisition, financing, contracting and managing profit and nonprofit organizations for organization to be viable and competitive. Leadership is involved in being capable of moving others forward to achieve strategic vision and his skills are strategic planning, financial development, mentoring and communication. Management is involved in putting in place all infrastructure and processes for effective working of organization. Vital management and business skills include team building, development of product and service, human resource development and marketing.

Mississippi Department of corrections Fails Essay

Mississippi Department of corrections Fails to provide proper care and fulfill their constitutional obligations to prisoners in privately owned prison. MDOC considers themselves above the law, and fails to hold up their responsibilities under constitutional laws. They do what they want when they want without concern to anyone. They do not provide adequate and safe meals, nor do they provide proper health care, and in general do not abide by the Mississippi state laws they have committed to punishing others for. They give contracts to privately owned companies from other states, whom honestly could care less about the inmates or the people of Mississippi and are only taking the contracts for the purpose of money gain. MDOC hit with lawsuit over† Inhumane conditions† at prison!!! Chris Davis on May 30th, 2013 filed a lawsuit in Jackson, Ms. Thursday by the American Civil Liberties Union and the Southern poverty Law alleges the Mississippi Department of Corrections has forgotten it’s constitutional obligations to its prisoners at the East Mississippi Correctional facility, a privately run prison under state supervision in Lauderdale County. The suit seeks â€Å"injunctive relief† meaning Mississippi must improve conditions to the satisfaction of the plaintiffs to settle the suit â€Å" East Mississippi Correctional Facility is a destination for individuals who suffer from mental illness†, says Owens. Unfortunately, while they are supposed to get treatment, they get nothing of the like. The conduct that happens there is a shock to the conscience of a civilized society. The most vulnerable continue to be exploited, abused and in some cases tortured. There are also situations where inmates are not provided with proper care or living conditions. (Judy Owens Audio)† some of the conditions are inmates who ask for treatment have been responded to with fire extinguishers and/ or faced with pepper spray, just for asking for help. News Mississippi immediately reached out to the Ms. Dept. of Corrections for their reaction and their comment was; â€Å"we have not been served, we will respond in court,† sa id spokesperson Tara Booth. Owens said the SPLC tried to meet with MDOC but was turned down. Owens also says he knows about budget problems within the department but he believes that does not relieve them of their constitutional obligations to prisoners. â€Å"This is a case about decency and treating people with respect,† said ACLU Att. Gabe Eber. † When you take a group of seriously mentally ill people and house them in filthy conditions, deny them basic medical and mental health care, you beat them and let them suffer abuse†¦. that’s a predictable recipe for disaster, But it’s got a fix!!! www. newsms. m/corrections-hit-with-lawsuit-over-inhumane-conditions-at-prison- We need a plan to fix the prisons and a commitment to follow through with that plan. I personally believe one solution to fix this problem is that Mississippi should manage their own prisons and stop hiring the job out to private out of state management contractors, that could care less about the people in our state . This would also save our state a lot of money to go toward much better things like homeless shelters for our homeless people or to feed our hungry people. What do you think? Shouldn’t Mississippi take care of their own?

Oedipus Rex2 essays

Oedipus Rex2 essays In Sophocless play Oedipus Rex Oedipus Even though "fate" seems to determine Oedipus' life, . he does infact have a free will. His choices brought the prophecy to life. Only his decisions (not influenced by anybody) he made. Of course those decisions were in side of the limits set by fate. When Oedipus heard a prophesy that his going to kill his father and sleep with his mother he ran away, even when he new there were suspicions of him being the real son of his parents. There some lines from the play: "...There was a man dining with us one day who had too much wine and man shouted at me-half drunk and shouting that I was not rightly called my father's son. ... Without my parent's knowledge, I went to Delphi, but Apollo did not say what I had gone to hear. Instead, he answered questions I had not asked and told of horror and misery beyond believe - how I would know my mothers bad ... and cause the death of my own father." The prophecy drove the Oedipus away from home; the terror of th e predictions was too much to live with. Oedipus tried everything not to meet the prophecy, and still when he came to Thebes and became a king Oedipus married an older lady. It was his choice, even when he knew there was a danger of him to know mothers bad, he made it. Oedipus' quest for truth was his choice. When the Teiresias tried not to reveal the truth, The Oedipus was the one, who made the priest to talk: "This city gave you life and yet you refuse to answer! You speak as if you were her enemy. ... For God's sake, if you know, don't turn away from us! We are pleading. We are begging you. ... You will not tell? You monster! You could stir the stones of earth to a burning rage! You will newer tell? What it will take?" As the truth is getting revealed: "... You, Oedipus, are the desecrator, the polluter of this land." Oedipus does not believe (his choice). He (Oedipus) start to accuse Creon of truing to take his powers away (king). And ...

Simple French Verb Conjugations for Louer (to Rent)

Simple French Verb Conjugations for Louer (to Rent) The French verb  louer  means to rent. When you need to say rented, renting, or will rent a conjugation is required. French students will be delighted to know that this ones pretty easy because it follows the most common verb conjugation pattern found in the language. Conjugations of the French Verb  Louer Louer is a regular -er verb and the endings required in the conjugations follow the pattern of similar words. If you know how to conjugate inviter (to invite), fumer (to smoke), or any other verbs that end in -er, then this will be an easy lesson. The trick to French verb conjugations is that the ending changes with the subject pronoun as well as the past, future, or present tense. First, you must identify the verb stem and in this case, that is  lou-.   With that information, follow the table to discover the appropriate endings for each form of  louer. For example, I am renting is je loue and we will rent is nous louerons. Practicing these in context using simple sentences will make them easier to memorize. Subject Present Future Imperfect je loue louerai louais tu loues loueras louais il loue louera louait nous louons louerons louions vous louez louerez louiez ils louent loueront louaient The Present Participle of  Louer The present participle of louer  is louant. This was formed by simply adding -ant  to the verb stem. Beyond its use as a verb, it can also become an adjective, gerund, or noun when needed. The Passà © Composà © and Past Participle The  passà © composà ©Ã‚  is a common way to express the past tense in French. Its very easy and requires the use of the  past participle  louà ©. In order to complete the construction, conjugate the auxiliary verb  avoir  to fit the subject pronoun. For instance, I rented becomes jai louà © while we rented is nous avons louà ©. Notice how ai  and avons are conjugates of avoir, yet the past participle does not change. More Simple Louer  Conjugations to Learn Those are the most important conjugations of  louer  that you should know. Once you learn those, consider studying these other simple forms. The subjunctive verb mood is used when the action of renting is uncertain. Similarly, the conditional verb mood implies that the renting will only happen if something else does. In formal French writing, you will likely come across the passà © simple and imperfect subjunctive as these are literary verb forms. Subject Subjunctive Conditional Pass Simple Imperfect Subjunctive je loue louerais louai louasse tu loues louerais louas louasses il loue louerait loua lout nous louions louerions loumes louassions vous louiez loueriez loutes louassiez ils louent loueraient lourent louassent The imperative verb form is used in short demands and exclamations. When using it, skip the subject pronoun: use loue instead of tu loue. Imperative (tu) loue (nous) louons (vous) louez

A Trench Fill Foundation Assignment Example | Topics and Well Written Essays - 500 words - 1

A Trench Fill Foundation - Assignment Example Since the ground condition has firm clay, therefore there is a need to consider the depth of foundations. Clay exhibits the property to shrink or contract depending on the moisture content present in it (Kenneth, 1993:25). At the same time, if the surrounding area has trees, there is a possibility that the trees would absorb the moisture from the clay and hence, the foundation may experience settlement to a significant level. For this case, it is essential to consider the depth of the foundation. A trench fill foundation is thus ideal for this type of site condition. Research suggests that â€Å"trench fill foundations are quicker to prepare than deep strip foundations. This means that there is less disruption once the building work starts and not as much labour time will be needed. It is less likely that subsidence will occur in cases where there may be changes in the soil's substrata† (Mosley & Bungey, 2000, 48).   The site has different ground conditions and has different soils. Thus, it has a weak bearing capacity. For this purpose, the ideal foundation would be strip, grid or mat foundation. In this case, the suggested foundation is mat foundation. Because of varying ground conditions, majority of the isolated footings would have large areas and thus, it would become uneconomical (Terzaghi et.al, 2006, 256)l. According to the British Code, â€Å"Where the subsoil is very weak the load needs to be spread over a greater area. This is achieved by casting a slab of concrete over the whole ground area and thickening the slab where walls are to be placed†(Perry & Perry, 2009, 118). The design of any reinforced concrete structure aims at a suitable and economical design and for this purpose, mat foundation is ideal. A mat foundation is often used by designers when isolated footings may overlap with one another (Fleming et.al, 2005: 198). A mat foundation is considered to be that type of foundation, which is placed over the entire area. It comprises of reinforced concrete slab, which would be laid over the uneven ground and thus, it would bear the load of the entire structure.   Mat foundation is also ideal for this type of ground condition because of differential settlement. The aim of the mat foundation is to minimize differential settlement (Coduto, 2001, 289). The massive loading of the structure can cause the soil to compress and thus, the structure may experience settlement. For this purpose, the mat is used as an option in order to distribute the entire loads of the buildings and to remove differential settlement.   

Genetic Engineering Process Essay Example | Topics and Well Written Essays - 750 words

Genetic Engineering Process - Essay Example An example is cry 1Ab which is a gene that codes certain insecticidal proteins in bacillius thiurengesis, which is a soil bacterium (University of Nebraska 2013). Agorabacterium tumefaciens is another example. 2. Gene insertion An essential component is plasmids, which are minute, self-replicating, circular DNA strands in the bacterial cells. Plasmids are easy to manipulate since they carry few genes and therefore provides routes for new gene introduction to cells (Wolfe 2013). Plasmids are used as the transfer channels. For agorabacterium tumefaciens, which is also a soil bacterium, genes are inserted using recombinant DNA methods. The bacterium possesses a plasmid (Ti). T DNA segment of the bacterium DNA carry genes that lead to tumour formation when it integrates in the maize DNA. However, manipulation of the genes by inserting new ones causes a disruption that makes the maize resistant to frost diseases and herbicides. Restriction endonuclease cleave the Ti plasmid exposing it to introduction of a foreign DNA from another source cleaved by the same enzyme. The genes are connected to the ends of the plasmids; thereafter ligation enzymes seal the ends and reform a structured DNA circle. The manipulated plasmid is then replaced into the bacterium. Antibiotic resistant marker genes must be included in the plasmids; the essence of the marker gene is to provide identification of cells containing the manipulated plasmids. Polymerase chain reaction takes over at this point, where genes are produced en masse. 3. Transformation Introducing plasmids into the organism of interest is through transformation. A few techniques can be employeds for transformation. However, the general concept involves attachment of A. Tumefasciencs to the organism’s cell, in this context the maize maize cell, and transferring a copy of the modified plasmid into the cell. Other methods of transformation other than use of A. Tumefasciens include particle bombardment and protoplast tran sformation. In particle bombardment, tiny tungsten beads with DNA coating of desired traits are shot into small fragments of maize cells that combine and integrate in to the maizes genome. The disadvantage of this method is that it results in unpredictable and unstable gene expression due to multiple copies of the introduced gene. Protoplasm transformation involves enzyme treatment of cell by stripping cell of their cell walls to form protoplast. Osmotic stress is induced to the protoplast in order to take up DNA in the protoplast’s surrounding (GMO education Network n.d). Inducing osmotic stress is by administering electrical shocks to the protoplast or by chemical treatment using polyethylene glycol. The protoplasts are thereafter regenerated into maizes using hormones. The problem with this method is that it is tedious and challenging. However, protoplasm transformation gives accurate and precise outcomes. 4. Selection of modified cells The selection process involves ident ification of cells that have obtained the manipulated plasmids into their genome. In genetic modified food industry, it is advisable to use the marker less insertion system to avoid the risk of marker gene expression in the maize. Typically, marker less transgenic involves screening numerous progeny