PhysioEx 9 Lab Report

11/6/2019 PhysioEx Exercise 9 Activity 6 PhysioEx Lab Report Exercise 9: Renal System Physiology Activity 6: The Effect of Hormones on Urine Formation Name: Date: 6 November 2019 Pre-lab Quiz Results You scored 100% by answering 5 out of 5 questions correctly. 1 Which of the following has a role in altering the urine volume and concentration? You correctly answered: all of these. 2 The total solute concentration surrounding the tubule lumen refers to the solutes in You correctly answered: the interstitial space. 3 Aldosterone is produced in the You correctly answered: adrenal cortex. 4 ADH promotes the renal reabsorption of You correctly answered: water. 5 Aldosterone promotes renal reabsorption of __________ and secretion of __________. You correctly answered: NaCl, potassium. Experiment Results Predict Questions 1 Predict Question 1: What will happen to the urine volume (compared with baseline) when aldosterone is added to the distal tubule? Your answer: The urine volume will decrease. 2 Predict Question 2: What will happen to the urine volume (compared with baseline) when ADH is added to the collecting duct? Your answer: The urine volume will decrease. 1/4 11/6/2019 PhysioEx Exercise 9 Activity 6 3 Predict Question 3: What will happen to the urine volume and the urine concentration (compared with baseline) in the presence of both aldosterone and ADH? Your answer: The urine volume will decrease and the urine concentration will increase. Stop & Think Questions 1 Why is the concentration in the urinary bladder 100 mOsm? You correctly answered: No ADH has been added to this nephron. 2 In the presence of aldosterone, what component of the tubule fluid moves out of the distal tubule and into the interstitial space? You correctly answered: NaCl. 3 In the presence of ADH, why did the urinary potassium concentration increase? You correctly answered: The water volume in the urinary bladder is decreased, increasing the concentration of solutes such as potassium. 4 In the presence of both ADH and aldosterone, why did the urinary potassium concentration increase? You correctly answered: There was more potassium secretion into the distal tubule and more water reabsorption in the collecting duct. Experiment Data Potassium Conc. in Urine (mOsm) Urine Volume (ml) 6.25 201.00 10.42 62.37 65.37 Urine Conc. (mOsm) Conc. Grad. (mOsm) Aldosterone ADH 100 1200 absent absent 180.90 100 1200 present absent 16.86 1200 1200 absent present 12.67 1200 1200 present present Post-lab Quiz Results You scored 100% by answering 4 out of 4 questions correctly. 1 If there has been a significant loss of fluid from the body, the kidneys will generate __________ urine. You correctly answered: hyperosmotic. 2 If you drink a large volume of water, the kidneys will generate __________ urine. You correctly answered: hypo-osmotic. 2/4 11/6/2019 PhysioEx Exercise 9 Activity 6 3 In response to dehydration, ADH will be released from the You correctly answered: posterior pituitary gland. 4 In response to abnormally low plasma osmolality, aldosterone will increase You correctly answered: sodium reabsorption along the distal tubule and the collecting duct. Review Sheet Results 1 How did the addition of aldosterone affect urine volume (compared with baseline)? Can the reabsorption of solutes influence water reabsorption in the nephron? Explain. How well did the results compare with your prediction? Your answer: When aldosterone was added it affected the urine by it causing a slight increase in the potassium concentration and a slight decrease in volume compared to the baseline values. There is a reabsorption of NaCl in the distal tubule that occurs. Water can also be absorbed during reabsorption of NaCl which contributes to the urine volume decreasing. 2 How did the addition of ADH affect urine volume (compared with baseline)? How well did the results compare with your prediction? Why did the addition of ADH also affect the concentration of potassium in urine (compared with baseline)? Your answer: I predicted that the urine volume was decrease and with viewing the data you can see that the ADH to the collecting duct resulted in a large decrease of urine volume compared to the baseline values. ADH also caused a large increase in potassium concentration. 3 What is the principal determinant for the release of aldosterone from the adrenal cortex? Your answer: The principal determinant for the release of aldosterone from the adrenal cortex is a decrease in blood pressure, detected by the cells in the afferent arteriole that trigger the release of angiotensin 2 by endothelial cells. 4 How did the addition of both aldosterone and ADH affect urine volume (compared with baseline)? How well did the results compare with your prediction? Your answer: I predicted that whenever both aldosterone and ADH were added to the distal tubule the urine volume would decrease and the urine concentration would increase. When 3/4 11/6/2019 PhysioEx Exercise 9 Activity 6 aldosterone and ADH were both added to the distal tubule, it resulted in an increase in urine concentration and a decrease in urine volume compared to the baseline values. 5 What is the principal determinant for the release of ADH from the posterior pituitary gland? Does ADH favor the formation of dilute or concentrated urine? Explain why. Your answer: Whenever there is a decrease in osmolarity, the posterior pituitary gland releases ADH. ADH favors the formation of concentrated urine. This can be seen in the data when ADH is present the urine concentration increases as the urine volume decreases. 6 Which hormone (aldosterone or ADH) has the greater effect on urine volume? Why? Your answer: ADH has the greater effect on urine volume. The urine volume drastically decreases from the baseline value of 201 ml to 16.86 ml whenever ADH was added. This is because ADH increases the amount of water reabsorbed in the distal tubule, thus decreasing the urine volume. 7 If ADH is not available, can the urine concentration still vary? Explain your answer. Your answer: Based on the data if ADH is unavailable urine concentration cannot still vary. However, urine volume can still vary without ADH. When only aldosterone is added, the urine concentration stays the same as the baseline value of 100 mOsm. However, when only ADH is added, the data shows an increase in urine concentration from 100 mOsm, at the baseline value, to 1200 mOsm. Thus showing that ADH mainly affects urine concentration. 8 Consider this situation: you want to reabsorb sodium ions but you do not want to increase the volume of the blood by reabsorbing large amounts of water from the filtrate. Assuming that aldosterone and ADH are both present, how would you adjust the hormones to accomplish the task? Your answer: In order to reabsorb sodium ions and not increase the volume of blood, you would have to decrease the amount of ADH. This is because ADH increases the ability to reabsorb water, which increases the volume of the blood. Therefore ADH must be decreased, as well as, increasing aldosterone. Aldosterone must be increased because is will reabsorb the sodium ions at a faster rate. 4/4