Need answers for question 2 and 3 NTR20003 PHYSIOLOGY IN MEDICAL AND HEALTH SCIENCES Final Assessment 2022 Topic 1: Gastrointestinal physiology (10 marks) In Practical 3: ‘Effects of a High Fat or High Carbohydrate (CHO) Meal on Metabolism and Metabolic Flexibility’ we examined the effects of high fat and high CHO intake on glycaemic response, substrate oxidation and metabolic flexibility. Following this experiment, we decided to recruit more participants and perform a follow-up experiment. This time, we replaced the high fat meal with a mixed meal (50% protein and 50% fat) and examined the effects of the respective meals on gastrointestinal hormone regulation. The new experiment included 10 participants consuming a high carbohydrate meal (>95% CHO) and 10 participants consuming a mixed meal (50% protein and 50% fat). Question 1. Answer the following questions by completing Table 1. a). In the experiment, you have measured hormones Gastrin, Cholecystokinin (CCK), Gastric Inhibitory Polypeptide (GIP), Secretin, and Motilin over a 2 hour period following consumption of both meals. In column 2 below, indicate any changes (i.e. increase, decrease or no change in hormone levels) following consumption of the two different meals (High CHO and Mixed Meal). (5 marks) b) For the hormone(s) that were identified as increasing in response to the meal, explain: • In column 3, the mechanism(s) behind their secretion (i.e. what is the stimuli for their secretion) (2.5 marks) and • In column 4, what is their role when secreted? (2.5 marks) *Please note: only comment on the hormones that are secreted (released) in response to the respective meal. Table 1. The response to a meal with high carbohydrate intake: Hormones——–Changes———Stimulus of Secretion———–Role When Secreted Gastrin————No Change CCK—————No Change GIP—————- increase————-Absorbance of glucose and fatty acids——–Once secreted it stimulates pancreatic beta cells to launch insulin, as a consequence facilitates in controlling blood glucose level. Secretin——–Increase———Secretion of Gastric acid————–It controls the secretion of pancreatic bicarbonate Motilin———-Increase———-Appearance of lipid——————It enhances gastric motility, promotes insulin secretion, and inhibits gastric regulation. The response to a mixed meal intake: Hormones——Changes——–Stimulus of Secretion——Role when Secreted Gastrin ——–Increase——-The stretching of the stomach wall, increase in the levels of stomach PH———Stimulates the secretion of Pepsine and Hcl CCK———Increase——–It’s stimulated by the appearance of fatty acids, Hcl and amino acids in the stomach——-Promotes the gall bladder to secrete bile to digest the fat GIP——-Increase——–Stimulated by the the uptake and absorbance of glucose and fatty acids———Promotes the secretion of insulin Secretin——Increase Motilin——-Increase———-NA————-Promotes the emptying of the gall bladder
Topic 2: Renal physiology (20 marks) In Practical 4 ‘Control of Fluid Balance’ volunteers consumed the following: • Treatment 1 – 8 ml water/kg body weight • Treatment 2 – 8 ml isotonic saline/kg body weight • Treatment 3 – 8 ml water/kg body weight, then exercised by stepping on and off a box for five minutes after fluid ingestion and before voiding urine for collection. In a different experiment, we changed treatment 2 and added a fourth group. Therefore, the new treatments were: • Treatment 1 – 8 ml water/kg body weight • Treatment 2 – 8 ml hypertonic saline/kg body weight • Treatment 3 – 8 ml water/kg body weight, then exercised by stepping on and off a box for five minutes after fluid ingestion and before voiding urine for collection. • Treatment 4 – Drink 0.8 ml vodka/kg body weight In the table below, explain the effects of each treatment on extracellular volume (2 marks), osmolality (2 marks) and urine volume (1 mark). Table 2. Extracellular volume Osmolality Urine Volume Treatment 1 Treatment 2 Treatment 3 Treatment 4 *Please note: Do not just state increase or decrease, explain why it (i.e. urine volume) changed or didn’t change. Name: _____________________________ Student ID:__________________
Topic 3: Cardio-respiratory physiology (14 marks) In Practical 5 ‘Cardiovascular responses to exercise’, we had volunteers undertake upper and lower body exercise at different intensities. In a new experiment, we had one volunteer undertake an incremental exercise test to examine changes in both metabolic and respiratory variables. Each variable was measured at 4 different time points (%VO2max). Use the results from the Table below to discuss why the variables changed (increase, decrease or stayed same) from low intensity exercise (25% of VO2max) to high intensity exercise (100% of VO2max –exhaustion) (each variable (7) is worth 2 marks). For example, explain the physiological reason why PAO2 begins to increase at 50% VO2max. Similarly, but the opposite for PaO2, why does it decrease just after 50%? In addition, does an increase in PAO2 and decrease in PaO2 towards the end VO2 max have any impact on the performance of the individual? Table 3. Variable—–25% VO2max—–50% VO2max—–75% VO2max——100% VO2max——-Explanation PaO2mmHg—–98————–98———————95————————92 PAO2 mmHg—-104———–105——————-110———————–117 PaCO2 mmHg—-44————44——————–39————————-30 Pulmonary Ventilation (VE, l.min)———–35—-55—–80——140 Arterial pH———7.4———–7.4——————-7.35———————–7.1 Femoral PVCO2—58———-61——————–64————————-67 – Femoral PVO2—-25———-22——————-20————————-15
Topic 4: Immune system (15 marks) Question 5. Explain how vaccinations protect against diseases. Specifically, discuss the immune cells involved in providing immunity. (8 marks) Question 6. Explain why some vaccinations need a “booster shot”. (2 marks) Question 7: The microbiome contains an ecosystem of microorganisms/foreign antigens. Why doesn’t the body attack the gut? (5 marks) Please use the space below and the next page (if needed) to answer question 5-7 Q5) When a cell is exposed to a vaccination, antibodies are created against the virus in the cell, and memory B cells assist to prevent additional infection if the virus infects in the future. Memory B cells divide to make plasma B cells and memory B cells, the memory B cells will recall the properties of the antigen that first stimulated their parent B cell and triggers a secondary immune response. Q6) When the first dosage of a vaccine is insufficient to induce an adequate immunological response, a booster dose is required. When a booster dosage is required to restore immunity levels to baseline, the immunological memory for that specific antigen begins to deteriorate. Q7) The immune system is capable of self-nonself tolerance. Self-antigens are introduced to lymphocytes during development in order for them to disregard them. They only get activated when they come into contact with foreign antigens. The gut microbiota plays an important role in health maintenance. They aid digestion, absorption, and nutritional absorption. These cells are not native to the human body. If they are detected by the host immune system, they will be eradicated. As a result, there has to be a mechanism in place to confer immunological tolerance to these bacteria. Stromal cells from adjacent lymph nodes give this immunological tolerance. They display normal-cell antigens to lymphocytes despite the fact that they will be not professional antigen-presenting cells.