EXERCISE 9: RENAL SYSTEM PHYSIOLOGY
Here is 9 got 95% Still need help on final 132
ACTIVITY 1: The Effect of Arteriole Radius on Glomerular Filtration Answers
1. According to your lab manual, in humans the glomerular filtration rate (GFR) ranges from _____ to _____ ml/minute. 80
140
2. When the radii of both the afferent arteriole and efferent arteriole were set at 0.45mm, the GFR was approximately ______ ml/minute.
a. 40
b. 60
c. 80
d. 120 C.
3. True or False: Drinking a lot of caffeine (coffee or cola) leads to an increased urine volume. This might result from a decrease in the radius of the efferent arteriole. True
4. What are two primary functions of the kidney? Excretion-filters water and solutes in the blood, the kidneys are able to excrete excess water
Regulation- regulates plasma osmolarity which is the concentration of solution expressed as osmoles of solute per liter of solvent, plasma volume, body’s acid-base balance, and body’s electrolyte balance.
5. What are the components of the renal corpuscle? Bowman’s capsule- renal corpuscle consist of a ball of capillaries called glomerulus and enclosed by a fluid-filled capsule called Bowman’s capsule
Glomerular Capillaries- this is another name for the renal corpuscle. An afferent arteriole supplies the blood to the glomerulus. The blood flows through the glomerular capillaries, protein-free plasma filters into the Bowman’s capsule, and known as the glomerular filtration. The afferent arteriole then drains glomerulus of the remaining blood.
6. Starting at the renal corpuscle, list the components of the renal tubule as they are encountered by filtrate. 1.Proximal convoluted tubule
2.Loop of Henle (U-shaped hairpin loop)
3.Distal convoluted tubule- before emptying into a collecting duct, from collecting duct, filtrate flows and collects in the minor calyces.
7. Describe the effect of decreasing the afferent arteriole radius on glomerular capillary pressure and filtration rate. By decreasing the afferent arteriole radius, this increases the glomerular filtration rate and pressure increases.
8. Describe the effect of increasing the afferent arteriole radius on glomerular capillary pressure and filtration rate. Increasing afferent arteriole radius, glomerular capillary pressure and filtration rate increases.
9. Describe the effect of decreasing the efferent arteriole radius on glomerular capillary pressure and filtration rate. Efferdent arteriole radius is decreased, glomerular filtration rate would increase.
10. Describe the effect of increasing the efferent arteriole radius on glomerular capillary pressure and filtration rate. Efferent arteriole radius if increased, the glomerular filtration rate would decrease.
ACTIVITY 2: The Effect of Pressure on Glomerular Filtration
11. True or False: In humans, glomerular capillaries can filter as much as 180 liters of filtrate in 24 hours. True
12. In this simulation, when the radius of the afferent arteriole was 50mm, the radius of the efferent arteriole was 0.45mm, and the beaker pressure was set to 100mmHg, the GFR was approximately _____ ml/min. 158.20
13. When the valve between the collecting duct and the urinary bladder was closed and when the beaker pressure was 100mmHg, the GFR was approximately _____ ml/min and the urine volume was approximately ______ ml.
a. 100; 100
b. 110; 50
c. 60; 0
d. 110; 0 D.
14. As the systemic blood pressure increased, what happened to the glomerular capillary pressure and the GFR? As the systemic blood pressure increased, the glomerular capillary pressure and GFR increased.
15. Compare the urine volume in your baseline data with the urine volume as you increased the systemic blood pressure. Urine volume was increased as systemic blood pressure increased.
16. How could the change in urine volume with the increase in blood pressure be viewed as being beneficial to the body? Increased urine volume causes more filtrates such as salt to be excreted. This can affect any harming effects of accumulating excess fluid or waste. The increase of blood pressure can increase blood volume and the increase of urine volume will help to stabilize blood volume.
17. When the one-way valve between the collecting duct and the urinary bladder was closed, what happened to the filtrate pressure in Bowman’s capsule (was not directly measured) and the GFR? The filtrate pressure and GFR increased.
18. How did increasing the systemic blood pressure alter the results when the valve was closed? Increase in blood pressure can be increase in blood volume. An increase in urine volume can stabilize blood volume. Increase of pressure caused GFR to increase.
ACTIVITY 3: Renal Response to Altered Blood Pressure
19. True or False: The renal system (the kidneys) is very important in regulating plasma osmolarity, plasma volume, and the body’s electrolyte balance. True
20. In this simulation, when the radius of the afferent arteriole was 0.60mm, the radius of the efferent arteriole was 0.45mm, and the beaker pressure was 70mmHg, the GFR was approximately _______ mm/min. 114.72
21. When the radius of the afferent arteriole was 0.60mm, the radius of the efferent arteriole was 0.35mm, and the beaker pressure was 70mmHg, the urine volume changed to approximately ______ ml.
a. 50
b. 80
c. 200
d. 240 D
22. List the several “mechanisms” you have explored that change the GFR. How does each of them specifically alter the GFR? Renal mechanisms have effects on water excretion . GFR is large compared to the amount of urine produced. Most water in the filtrate because of renal processes and independent of ADH action (Brandis, 2001):
1.Glomerulotubular Balance- this is a local renal mechanism. The proximal tubule is involved, and changes in oncotic pressure. Changes in hydrostatic pressure and delivery of certain solutes. When GFR increases protein concentration in efferent arteriole increases. Along with increase in oncotic pressure in peritubular capillaries. Increased gradient for reabsorption and balances increasing GFR on volume of fluid exiting proximal tubule.
2.Auto-regulation of Blood flow- This affects water excretion, when renal perfusion pressure increases. The afferent arterioles vasco-constrict and renal plasma flow and GFR are constant. Urine flow is not auto-regulated. The rise in blood pressure will increase urine flow, and GFR is slightly affected.
3.Intrinsic Pressure- Volume Control System- This maintains constant blood volume- pressure diuresis and pressure natriuresis.
The kidneys regulate excreting water and sodium into urine, to regulate blood volume (Klabunde, 1998-2010):
1.Activation of renin-angiotensin-aldosterne system increases sodium retention and reduces water loss into urine. This occurs in renal artery stenosis and can cause secondary hypertension.
2.Use of ADH (antidiuretic hormone) which is released by posterior pituitary. This simulates water reabsorption in collection duct, and decreases water loss and increases blood volume.
3.Blood volume affects arterial pressure and change cardiac output. Increase in blood volume increases central venous pressure. This causes increase in the right atrial, right ventricular and volume.
23. Describe and explain what happened to the glomerular capillary pressure and GFR when both arteriole radii changes were implemented simultaneously with the low blood pressure condition. The simultaneously implementation of both arteriole rates changing caused glomerular filtration rate and low blood pressure conditions went above the baseline value.
24. Which arteriole radius adjustment was more effective at compensating for the effect of low blood pressure on the GFR? There was a greater increase of glomerular pressure when afferent radius is increased rather than the decrease of the efferent radius.
ACTIVITY 4: Solute Gradients and Their Impact on Urine Concentration
25. Antidiuretic hormone (ADH)
a. is synthesized in the hypothalamus and secreted from the posterior pituitary gland.
b. affects the reabsorption of water in the kidneys.
c. if absent from the body, results in a condition named diabetes insipidus.
d. All of the above are correct. D.
26. If a person is very dehydrated, compared to normal, the urine volume will ______ and the concentration of the urine will ________.
a. increase; increase
b. increase; decrease
c. decrease; increase
d. decrease; decrease C.
27. True or False: ADH affects water reabsorption by its effect on the glomerular arterioles. False
28. What happened to the urine concentration as the solute concentration in the interstitital space was increased? Concentration of urine was increased.
29. What happened to the volume of urine as the solute concentration in the interstitial space was increased? The volume of urine decreased.
30. What do you think would happen to the urine volume if you did not add ADH to the collecting duct? Without adding ADH to the collecting duct, urine volume would increase highly and no significant amount of water permeability would be in collecting duct or distal tubule. Less water is reabsorbed, so more urine is formed
31. Is most of the tubule filtrate reabsorbed into the blood stream (the body) or excreted in urine? Explain. To maintain homeostasis balance and loss of fluid, most tubule filtrate is reabsorbed into the blood stream.
ACTIVITY 5: Reabsorption of Glucose via Carrier Proteins
35. True or False: Renal processing of glucose that is filtered in the glomeruli is primarily by secretion back into the blood stream. True
36. In this simulation, you varied the number of glucose carriers. When the glucose concentration in the tubules and urinary bladder became zero, the total number of glucose carriers was ______.
400
37. True or False: The kidneys of a person with type 1 diabetes are able to synthesize extra glucose carrier molecules so that no glucose is excreted in urine. False
38. When there were 200 glucose carriers, the glucose concentration in the distal tubule and urinary bladder was approximately
a. 0
b. 2.5
c. 5
d. 10 B
39. What happens to the concentration of glucose in the urinary bladder as the number of glucose carriers increases? There is a decrease in the glucose concentration. The carriers are able to carry glucose across the walls of the glomerulus for the reabsorption.
40. What types of transport are utilized during glucose reabsorption and where do they occur? The first absorption is by active transport. This occurs at the apical membrane of PCT cells. Then a facilitated diffusion along the basolateral membrane.
41. Why does the concentration of glucose in the urinary bladder become zero in these experiments? The concentration of glucose becomes zero because when 400 glucose carriers were added, enough were added to facilitate the re-up of glucose. This left nothing in the unabsorbed water and became urine.
42. A person with type 1 diabetes cannot make insulin in the pancreas; a person with type 2 diabetes does not respond normally to the insulin that is made in the pancreas. In either case, why (or when) would you expect to find glucose in the person’s urine? There is a high glucose concentration in the urine of a diabetic. With the lack of glucose carriers, a less amount of glucose is transported. A high amount of the glucose cannot be transported across and leaves a high concentration to be discarded with the formation of urine.
ACTIVITY 6: The Effect of Hormones on Urine Formation
43. The hormone aldosterone promotes renal absorption of _______ in the body and the secretion of _______ from the body.
a. Water; NaCl
b. sodium; potassium
c. NaCl; potassium
d. Glucose; NaCl C.
44. In this simulation, when both aldosterone and ADH were added, the concentration of potassium in the urine increased from approximately 6 to ______. 65.37
45. How did the addition of aldosterone affect urine volume (compared with baseline)? By adding the aldosterone, there was a slight increase in the potassium concentration of urine. This indicates the hormone has a re-absorption of potassium.
46. How did the addition of ADH affect urine volume (when compared with baseline)?
Why did the addition of ADH also affect the concentration of potassium in the urine (when compared with baseline)? Adding ADH increases urine and potassium concentration, and decreases urine volume.
This causes water to be absorbed from the urine back into the body. The potassium concentration is 10 times the amount without ADH, and urine volume is 1/10 without ADH.
47. What is the principal determinant for the release of aldosterone from the adrenal cortex? Aldosterone is stimulated by production of angiotensin II. The renin-angiotensin system in which the body controls this.
48. How did the addition of both aldosterone and ADH affect urine volume (compared with baseline)? Adding both aldosterone and ADH decreases urine volume. When both were absent the volume was 201.00 and decreased when both were present to 12.67
49. What is the principal determinant for the release of ADH from the posterior pituitary gland?
Does ADH favor the formation of dilute urine or of concentrated urine? Aldosterone is stimulated by producing angiotensin II and controlled by the renin-angiotensin system. Water is reabsorbed back into the blood and raises blood pressure.
ADH favors the formation of concentrated urine. ADH is to increase the permeability of the collection ducts, so more water is reabsorbed by the body. ADH is influenced by volume, pressure of cardiovascular system, and osmolality of fluids.
50. Which hormone (aldosterone or ADH) has the greater effect on urine volume? ADH causes decreases in the amount. ADH increases water permeability of the distal tubule, and collecting duct. This means more water can be reabsorbed making urine volume less and keep water balance. Aldosterone only decreases urine volume a small amount.
References
Brandis K., (2001). Research for Question 22: Fluid Physiology and other Mechanisms of Water Balance. Retrieved from:
http://www.anasthesiamcq.com/FluidBook/fl5_9.phpKlabunde R. E., (1998-2010). Research on Question 22: Blood volume. Retrieved from:
http://www.cvcphysiology.com/Blood%20Pressure/BP025.htmChang 19 to False