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Topics in Physiology Assignment PDF

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Added on  2021-06-17

Topics in Physiology Assignment PDF

   Added on 2021-06-17

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1Topics in PhysiologyNameDate of Submission
Topics in Physiology Assignment PDF_1
2Introduction The body of academic literature and scientific research indicates that there is a primarydifference between starvation and fasting. Starvation is simply the reductions in caloric energyintake within the human body (Thomas 2007). Fasting, on the other hand, comes by free will andis defined by abstaining from all or some kinds of foods or drinks for a short period of time(Sidhu and Naugler, 2012). Predominantly, the majority of religions believe that fasting is goodfor the soul (Trepanowski and Bloomer, 2010). There is no doubt that reduction in one’s dietcould be beneficial in different aspects. In saying that however, the human body is essentially amechanical machine that need certain nutrients, proteins and carbohydrates to function. One whois in a fasting or starving state lacks these essentials ingredients. It suffices to say, that if oneenters into the state of fasting or starvation, there exists a change in the biochemical andphysiological responses in the body. Following this, the main causes of starvation originate frommedical or circumstantial causes. Medical causes of starvation include, but are not limited to,Anorexia, Bulimia Nervosa, Eating Disorders, Celiac Disease, Major Depressive Disorder,Diabetes mellitus and Digestive disease. The main cases of circumstantial causes are specificallymotivated by political, social and economic interests. These motivations can manifest in differentforms, such as extreme diets, domestic violence and abuse, or famine which arises from politicalstrife, warfare and poverty. While one is enduring in a starvation state, there are three different phases the body reacts to this.GluconeogenesisFirstly, humans need to maintain proper blood glucoses levels above a certain concentration inorder to survive, which is essentially part of homeostasis (Gray et al., 2015). For example, let’sstart by having a mini case of starvation three or four hours after a meal your blood glucose
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3levels begin to drop so what your body begins to do is quickly turns to its glycogen stores in theliver, the only main issue with this is that our glycogen stores in the body only last us around24hrs are this the blood glucose levels begin to drop and the body need different methods to trybring that blood glucose levels back up. This is primarily where the metabolic pathways ingluconeogenesis comes into play this is the pathway where we produce new glucose. These newglucose molecules are produced from non-carbohydrate pre curser molecules (Hatting et al.,2018). Gluconeogenesis in humans involves the synthesis of glucose and glycogen from lactate,also pyruvate, glycerol and certain amino acids. The liver is the main organ for gluconeogenesiswhile the kidneys also become an important site during starvation.The body is always in the process if maintaining a balanced level of blood glucose to ensure thatenough of it is available especially for the vital organs like the brains tissues. Gluconeogenesisrefers to a pathway or process in which glucose molecules are synthesized from non-carbohydrate precursors. Gluconeogenesis occurs primarily in the liver although other sitesincluding the kidneys can support this process (Mithieux et al., 2017). for instance, under toughstarvation conditions, it is the cortex of the kidneys which supports gluconeogenesis. However,majority of the glucose made by the renal cortex is used by the renal medulla, while a fewamounts enters into the blood stream. Most of the processes in gluconeogenesis are similar toglycolysis. The enzymes in the two reverse processes are highly regulated so that at any giventime only one process occurs and not both. The most common amino acids used for synthesis ofglucose are alanine. Alanine is produced in the muscle tissues from other amino acids as well asglucose. For pyruvate to be used as a precursor, it must be sourced from anaerobic glycolysis insome tissues like erythrocytes, muscles and fat adipose tissues. On the other hand, glycerol as a
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4raw material is sourced from adipose stores of the fatty acids, while amino acids are generatedfrom the amino acid pools of the muscle tissues. KetosisThis is a metabolic process which takes place in the body especially when the body does nothave enough energy to sustain its activities and maintain hemostasis. In ketosis, the body burnsdown the stored fats leading to a buildup of ketones in the body cells (Paoli et al., 2015). As thelevels of the ketones build up, so does the acidity of the blood increases too. In some cases, thereare some people who observe a ketogenic or low carbohydrate diet so as to lose weight by usingfats to produce energy. When glucose amounts are not sufficient in the body, stored fats arebroken down to meet the body needs of glucose. In the end, ketones are formed as byproductsand are later eliminated in the urine. In low amounts, ketones signal that the body is breakingdown fats, but at high amounts, they become poisonous sue to the accumulation of ketone andgives rise to ketoacidosis. This process is initiated when the body is undergoing starvation andfasting leading to low or no glucose supply in the diet (LaManna et al., 2017).. Ketosis produces energy which can serve some vital organs, more so the brain. Three days afterthe starvation, the liver produces ketone bodies such as acetoacetate and hydroxybutyrate fromacetyl coA. This is because the Krebs cycle is unable to utilize all the available acetyl-coAmolecules produced from fatty acids degradation. At the same time, since during starvation thegluconeogenesis is active, this pathway ends up consuming the oxaloacetate which would becoupled to acetyl CoA in Krebs cycle. The brain uses considerable amounts of acetoacetate sinceglucose is unavailable during fasting and starvation (Cunnane et al., 2016). Following about
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