AnP 2.pdf

You will receive two questions from this group - one module 3 question, and one module 4 question. Remember that these questions are allocated to you randomly. You cannot choose which questions you will answer. Module 3 Question This questions relates to Renal System Regulation. Ms K, aged 47, suff...

You will receive two questions from this group - one module 3 question, and one module 4 question. Remember that these questions are allocated to you randomly. You cannot choose which questions you will answer. Module 3 Question This questions relates to Renal System Regulation. Ms K, aged 47, suffers from primary hyperaldosteronism. She is hypertensive with a blood pressure of 160/82 mmHg. Explain how primary hyperaldosteronism leads to high blood pressure (2 marks) Aldosterone stimulates the insertion of sodium/potassium pumps in cells of distal convoluted tubules and collecting ducts These leads to an increase in reabsorption of sodium ions, subsequently, in more water reabsorption This increases blood volume, which would increase blood pressure What changes would you expect to see in Ms K's blood electrolytes (1 mark)? We would see an excess of sodium and potassium ions. As the hormone, aldosterone, leads to an increase in reabsorption of sodium ions by stimulating the insertion of sodium/potassium pumps in cells of distal convoluted tubules and collecting ducts and promotes secretion of potassium ions by the cells in the collecting duct Before Ms K was diagnosed with primary hyperaldosteronism, her doctor prescribed her an angiotensin converting enzyme (ACE) inhibitor to try and treat her hypertension. ACE inhibitors work by inhibiting the enzyme (ACE) that forms Angiotensin II. Explain how an ACE inhibitor would be effective as an antihypertensive (3 marks). ACE inhibitors are able to acts as effective antihypertensives by influencing the renin-angiotensin-aldosterone-system (RAAS). Angiotensin converting enzyme (ACE), functions by converting angiotensin 1 into angiotensin 2. Angiotensin 2 is a powerful vasoconstrictor which narrows blood vessels, thus, increasing blood pressure. By inhibiting ACE, the blood pressure is maintained as angiotensin 1 is never converted. Moreover a decrease in angiotensin 2, results in a decrease in aldosterone, as angiotensin 2 stimulates the adrenal cortex to secrete aldosterone. This also has an effect on blood pressure, albeit, indirectly as aldosterone causes kidneys to retain sodium and water, which increases blood volume and, thus, increases blood pressure. ??? Loop diuretics are drugs that are also used to treat hypertension. These drugs inhibit the reabsorption of Na+ and Cl- ions by the ascending limb of the loop of Henle. Explain how loop diuretics would effect urine output (2 marks). Loop diuretics inhibit the reabsorption of sodium and chloride in the ascending loop of Henle. This increases the amount of sodium in the filtrate, pulling more water into the urine because sodium creates an osmotic gradient, where water follows the higher concentration of sodium in the filtrate to maintain balance, thereby increasing urine output. Module 3 Question This question relates to the Glomerular Filtration Membrane. Farouk Ali, aged 53, suffers from severe dehydrating diarrhea from food poisoning. List and describe the three pressures operating at the filtration membrane and explain how each influences net filtration pressure (6 marks). Glomerular blood hydrostatic pressure (GBHP) - Pushes water and solutes at around 55mmHg from blood through filtration membrane. As the pressure is going in the direction of the filter, it increases the net filtration pressure. Capsular hydrostatic pressure (CHP) - Pressure exerted at around 15mmHg by fluid in capsular space and renal tubule against the filtration membrane. As the pressure is going against the direction of the filter, it decreases the net filtration pressure. Blood colloid osmotic pressure (BCOP) - Typically at around 30mmHg, caused by proteins in the blood plasma and opposes filtration. As the pressure is going against the direction of the filter, it decreases the net filtration pressure. What effect will Farouk’s severe diarrhea have on net filtration pressure (2 marks)? - Severe diarrhea leads to dehydration, reducing GHP (lower blood volume) and increasing BCOP (less fluid, same proteins). NFP decreases, reducing filtration efficiency. - Net effect: The net filtration pressure would decrease, reducing glomerular filtration rate (GFR), which impairs the kidney's ability to filter waste efficiently. Module 4 Question This question relates to Gallbladder Function. Sally, aged 38, has had a cholecystectomy following complications associated with gallstones, a condition known as cholelithiasis. Her surgery went very well, and while her Dr said that she should have no problems digesting food, she has been experiencing recurrent episodes of diarrhea. Describe the digestive function of the gallbladder including its stimulatory regulation (4 marks). - Bile storage: The gallbladder stores bile produced by the liver, concentrating it between meals. - Bile release: During digestion, especially after consuming fatty foods, the gallbladder contracts and releases bile into the small intestine. - Fat emulsification: Bile emulsifies fats, breaking them into smaller droplets to aid in digestion and absorption. - Regulation: Gallbladder contraction is stimulated by the hormone cholecystokinin (CCK), which is released by the small intestine in response to fatty food entering the duodenum. Explain why digestion is minimally compromised following a cholecystectomy and why Sally might be experiencing episodes of diarrhea (4 marks). - Minimal impact on digestion: After a cholecystectomy, the liver still produces bile, but it drips continuously into the small intestine rather than being stored and released in bursts. This maintains enough bile for fat digestion, though the response to large fatty meals may be less efficient. Reason for diarrhea: - Without a gallbladder to regulate bile release, bile may continuously flow into the intestines, leading to irritation and faster transit time. This can cause bile acid diarrhea, as excess bile in the colon draws water into the stool, leading to loose bowel movements. Module 4 Question This question relates to Triglyceride Digestion. Triglycerides are the major dietary fat and energy source for the body. To obtain energy from triglycerides, it must first be ingested through food, digested in the digestive tract and absorbed into the blood stream. Outline how triglycerides are digested and how they and their constituents are absorbed in the human body (8 marks). ◦ In your discussion include the mechanical and chemical digestion processes from the point of ingestion and absorption process to the point where the triglycerides enter the bloodstream. Digestion and Absorption of Triglycerides (8 marks): 1 Mechanical digestion: ◦ In the mouth, chewing and in the stomach, churning breaks down fat droplets. 2 Emulsification: ◦ In the small intestine, bile salts from the liver/gallbladder emulsify fats into smaller droplets for easier enzyme action. 3 Chemical digestion: ◦ Pancreatic lipase breaks down triglycerides into monoglycerides and free fatty acids. 4 Micelle formation: ◦ These components combine with bile salts to form micelles that transport them to the intestinal lining. 5 Absorption into enterocytes: ◦ Inside intestinal cells, monoglycerides and fatty acids are reassembled into triglycerides. 6 Chylomicron formation: ◦ Triglycerides are packaged into chylomicrons for transport. 7 Transport: ◦ Chylomicrons enter the lymphatic system via lacteals and are delivered to the bloodstream through the thoracic duct. 8 Bloodstream: ◦ In the bloodstream, chylomicrons deliver triglycerides to tissues for energy or storage. Questions worth 4 marks You will receive one question from this group. Remember that these questions are allocated to you randomly. You cannot choose which questions you will answer. Module 3 Question This question relates to the Micturition Reflex. The micturition reflex requires a complex network of signals between the nervous system and the urinary tract. Urine storage and bladder emptying are highly dependent on these pathways. How does the detrusor muscle and the internal urethral sphincter respond to increased firing of the parasympathetic fibers that innervate it (1 mark)? The increased firing stimulates the detrusor muscle, which then contracts, thus, exerting pressure on the urine within the bladder, facilitating the release of urine in urination. In the case of the urethral sphincter it is inhibited by the brain, causing the urethral sphincter to relax, opening the passage between the bladder and the urethral sphincter, this relaxation allows urine to flow from the bladder into urethra allowing for expulsion from body What effect would a spinal cord injury that has damaged the sympathetic nerves at the L2–L5 region of the spinal cord have on the micturition reflex (3 marks)? The micturition reflex relies on signals between the brain and spinal cord. Damage to the L2–L5 region can disrupt these signals. Normally, stretch signals from the bladder activate the parasympathetic system, causing the detrusor muscle to contract and release urine. If these signals are impaired, it may lead to **urinary retention** or **incontinence**. The brain also controls the urethral sphincter, causing it to relax for urination. Damage could either make the sphincter relax involuntarily or stay contracted, depending on how the signals are affected. Module 3 Question This question relates to the Auto-regulatory Mechanism of GFR. The kidneys' ability to self-regulate the glomerular filtration rate (GFR) is a major factor that contributes to their function. Although the validity of these autoregulatory mechanisms is debated, understanding the proposed mechanisms is helpful. Choose One of the auto-regulatory mechanisms that likely contributes to the regulation of GFR, relative to a situation where the GFR is initially low (4 marks). An auto regulatory mechanism that contributes to the regulation of the glomerular filtration rate would be hormone regulation. This could come in the form of the release of atrial natriuretic peptide. This is stimulated by the stretching of the atria which stimulates the secretion of ANPP. This causes the relaxation of mesangial cells in glomerulus increases capillary surface area for filtration, which subsequent increases the GFR effect. Module 4 Question This question relates to the Accessory Organs of the Digestive Tract. Although they are not part of the digestive tract, the salivary glands, liver, gall bladder and pancreas are still digestive organs. Describe in general how each organ contributes to the digestion process (4 marks). Contribution of Accessory Organs to Digestion (4 marks): 1 Salivary glands: ◦ Produce saliva, containing amylase, which begins the digestion of carbohydrates in the mouth. 2 Liver: ◦ Produces bile, which emulsifies fats in the small intestine, aiding in fat digestion and absorption. 3 Gallbladder: ◦ Stores and concentrates bile from the liver, releasing it into the small intestine when needed for fat digestion. 4 Pancreas: ◦ Secretes pancreatic enzymes (lipase, amylase, proteases) and bicarbonate into the small intestine, essential for the digestion of fats, carbohydrates, proteins, and neutralizing stomach acid. Module 4 Question This question relates to the Gastric Secretion. Gastric juice is made up of digestive enzymes, hydrochloric acid and other substances that are important for absorbing nutrients. Why is it necessary for the stomach contents to be so acidic (2 marks)? Why the stomach contents must be acidic (2 marks): 1 Activation of pepsinogen: The stomach’s low pH (1.5-3.5) converts pepsinogen into its active form, pepsin, which is essential for protein digestion. 2 Defence against pathogens: The acidity helps kill bacteria and pathogens that are ingested with food. How does the stomach protect itself from digestion (2 marks) ? How the stomach protects itself from digestion (2 marks): 1 Mucus layer: The stomach lining secretes a thick mucus layer that acts as a physical barrier, preventing acid from damaging the epithelial cells. 2 Bicarbonate secretion: The stomach's cells also release bicarbonate, which neutralizes acid near the mucosal surface, maintaining a pH-safe environment for the tissue.