MCQ on Urinary System Physiology

1) The nephron is:
     a. the site of urine storage
     b. the functional unit of the kidney
     c. the site where ADH is produced
     d. also called the "Bowman's capsule"

2. Which of the following is NOT a stage of urine formation:
     a. glomerular filtration
     b. glomerular secretion
     c. tubular secretion
     d. tubular reabsorption

3. Which of the following is NOT a means of regulating glomerular filtration:
     a. muscular regulation
     b. renal autoregulation
     c. hormonal regulation
     d. neuronal regulation

4. Increased sympathetic nervous system stimulation of afferent arterioles results in:
     a. decreased filtrate production
     b. increased filtrate production
     c. no change in filtration rate
     d. increased kidney function

5. Renin is produced by:
     a. the glomerulus
     b. macula densa
     c. proximal convuluted tubule
     d. juxtaglomerular cells

6. The function of the macula densa cells is to:
     a. prevent water reabsorption in the ascending loop of Henle
     b. add bicarbonate ions to the tubular filtrate
     c. secrete renin in response to decreased afferent arteriole pressure
     d. monitor NaCl concentration in the filtrate
     e. reabsorb Na+ ions into blood from the filtrate

7. Atrial naturiuretic peptide works to:
     a. increase afferent arteriole pressure
     b. increase blood flow to the kidney
     c. enhance the effects of ADH
     d. inhibit the effects of aldosterone
     e. increase blood volume

8. If the level of aldosterone in the blood increases, then:
     a. less sodium is excreted in the urine
     b. less potassium is excreted in the urine
     c. systemic blood pressure will decrease
     d. glomerular filtration will decrease
     e. both c and d

9. The most important function of the juxtaglomerular apparatus (JGA) is to:
     a. secrete water and sodium into the filtrate
     b. reabsorb sodium
     c. generate bicarbonate ions in response to decreased blood pH
     d. secrete renin in response to decreased renal blood pressure or blood flow
     e. constrict the afferent arterioles and decrease sodium reabsorption

10. If the diameter of the afferent arteriole is smaller than the diameter of the efferent arteriole, then:
     a. the net filtration pressure will decrease
     b. blood pressure in the glomerulus will decrease
     c. GFR will increase
     d. a and b only
     e. a, b and c

11. From the distal convoluted tubule, filtrate will then be carried to the:
     a. renal corpuscle
     b. collecting duct
     c. nephron loop
     d. proximal convoluted tubule
     e. glomerular (Bowman's) capsule

12. In a patient who is dehydrated from vomiting and diarrhea, which is likely to be higher than normal in blood:
     a. ADH only
     b. aldosterone only
     c. ANP only
     d. both ADH and aldosterone
     e. both ADH and ANP

13. All of the following are normally found in urine except:
     a. glucose
     b. sodium ions
     c. uric acid
     d. urea
     e. creatinine

14. In some autoimmune diseases, capillaries may become damaged resulting in and high levels of albumin proteins and blood cells appearing in the urine. Which region of the nephron contains capillaries that, when damaged, could cause this appearance in urine:
     a. renal glomerulus
     b. proximal convoluted tubule
     c. nephron loop
     d. distal tubule

15. Regarding the renal circulation:

a) The kidneys receive about 10% of the resting cardiac output

b) As cardiac output increases during exercise renal blood flow rises.

c) Renal blood flow is maintained within narrow limits despite changes in arterial blood pressure.

d) Increased activity in the renal sympathetic nerves results in increased blood flow to the kidneys.

16. Regarding the glomerular filtration rate (GFR):

a) The GFR depends on the pressure in the afferent arterioles.

b) A substance that has a clearance less than the GFR must have been secreted by the renal tubules.

c) The glomerular filtration rate can be determined by measuring the clearance of insulin.

d) The glomerular filtrate has the same composition as plasma.

17. Regarding the transport of glucose by the renal tubules:

a) In a healthy person, the distal tubules reabsorb all of the filtered glucose.

b) Glucose is secreted into the urine in small quantities.

c) The transport maximum for glucose is about 36 mg min^-1.

d) Glucose transport by the renal tubules is linked to sodium transport.

18. Concerning the excretion of acid by the kidneys:

a) The filtered bicarbonate is absorbed by anion transport.

b) The intercalated cells of the distal tubule secrete hydrogen ions to reabsorb bicarbonate from the tubular fluid.

c) All of the filtered bicarbonate is normally reabsorbed in the first half of the distal tubule.

d) Urine pH is normally greater than that of plasma.

19. Regarding the control of water balance by the kidneys:

a) The renal medulla has an osmotic gradient that decreases from the border with the cortex to the renal papilla.

b) ADH is secreted by the anterior pituitary in response to a decrease in the osmolality of the blood.

c) A normal person cannot produce urine with an osmolality greater than 300 mOsmol.kg^-1.

d) ADH acts on the P cells of the collecting ducts to increase their permeability to water.

20. The term "renal autoregulation" refers in part to the fact that

A. the kidney does not require blood flow to sustain its active transport
B. the kidney contains baroreceptors (pressure receptors) that contribute to the regulation of cardiac output
C. renal blood flow is relatively constant over a wide range of systemic arterial pressures
D. renal blood flow is not affected by activation of the sympathetic nerves that innervate the kidney
E. a combination of both C and D above

21. The nerves that innervate the kidney are essential for regulating which of the following?

A. Na-K-ATPase active transport pump rate
B. renal autoregulation of blood flow
C. urine volume and tonicity (osmolality)
D. all of the above
E. none of the above

22. Which of the following would be expected to cause renal inulin (or creatinine) clearance to increase?

A. dilation of the afferent arteriole
B. dilation of the efferent arteriole
C. constriction of the afferent arteriole
D. constriction of the efferent arteriole
E. both A and D above

23. Kidney inflammation may result in the appearance of albumin (a plasma protein) in the urine because

A. more albumin enters the proximal tubule in the glomerular filtrate
B. reabsorption of albumin from the proximal tubule is inhibited
C. secretion of albumin into the distal tubule and collecting ducts is increased
D. increased peritubular blood flow makes more albumin available for diffusion into the tubule
E. reduced active transport of sodium ion reduces cotransport of other substances, including albumin

24. As blood passes along the glomerular capillaries from the afferent to efferent arteriole, the net filtration pressure (DP - Dp)

A. increases
B. decreases
C. first decreases, reaches a minimum about half way along the capillary, then increases
D. first increases, reaches a maximum about half way along the capillary, then decreases
E. remains constant

25. Sodium is actively reabsorbed from the renal tubule in which of the following nephron segments?

A. proximal tubule
B. distal tubule
C. thick ascending limb of the loop of Henle
D. all of the above
E. none of the above

26. The rate of water reabsorption from the proximal tubule is determined primarily by the

A. rate of dissolved particle (solute) reabsorption from the proximal tubule
B. concentration of ADH (antidiuretic hormone) in the blood
C. osmotic pressure developed by plasma proteins in the proximal tubule
D. active transport of water molecules by the proximal tubule cells
E. passive filtration due to the high hydrostatic pressure in the proximal tubule

27. Urea has a higher concentration in the fluid that leaves the proximal tubule (and enters the loop of Henle) than in blood plasma because

A. urea is synthesized by proximal tubule cells
B. urea is secreted into the proximal tubule
C. urea is reabsorbed from the proximal tubule but at a lesser rate that water is reabsorbed
D. urea diffuses back into the proximal tubule because of the high urea concentration in the renal medulla
E. urea is actively transported into Bowman's capsule from the glomerular capillaries

28. In the proximal tubule, penicillin is

A. actively secreted into the tubule
B. actively reabsorbed from the tubule
C. passively reabsorbed from the tubule
D. metabolized by the tubule cells
E. neither secreted nor reabsorbed nor metabolized

29. At which sites would the concentration of creatinine be expected to be highest? (Note: assume the person is normally hydrated.)

A. glomerular filtrate
B. end of the proximal tubule
C. end of the loop of Henle
D. urine
E. the concentration would be the same in all of the above, since creatinine is neither secreted or reabsorbed

30. Suppose a person loses the function of half his nephrons because of renal degenerative disease. Assuming the person survives and reaches a new steady state and that body urea production remains normal, which of the following would be expected to decrease below normal?

A. plasma urea concentration
B. renal urea excretion
C. renal urea clearance
D. urine urea concentration
E. all of the above

31. The following values are measured for potassium ion in a human subject.

Plasma K+                            5 meq/liter
Urine K+                               50 meq/liter
Renal creatinine clearance  80 ml/min
Urine formation rate             1.5 ml/minute

This patient's potassium clearance is closest to which of the following?

A.   5 ml/minute
B. 7.5 ml/minute
C. 15 ml/minute
D. 50 ml/minute
E. 75 ml/minute

32. Assuming the subject in the preceding question is a normal adult, we can conclude that most likely potassium is

A. filtered but not secreted or reabsorbed
B. secreted but not filtered or reabsorbed
C. reabsorbed but not secreted or filtered
D. filtered and secreted
E. filtered and reabsorbed

33. Stimulation of the osmoreceptors in the hypothalamus would be expected to cause all of the following to increase except

A. ADH release from the pituitary
B. water reabsorption from the renal collecting duct
C. rate of urine formation
D. osmolality of urine
E. none of the above; that is, none are exceptions since all would be expected to increase

33. As fluid passes along a juxtamedullary nephron, where is its osmolality (total concentration of dissolved particles) lowest? (Note: assume a normal concentration of circulating ADH.)

A. Bowman's capsule (glomerular filtrate)
B. fluid leaving the proximal tubule and entering the loop of Henle
C. fluid leaving the descending thin limb and entering the ascending thin limb of the loop of Henle
D. fluid leaving the thick ascending segment of the loop of Henle and entering the distal tubule
E. fluid leaving the collecting ducts (urine)

34 Drinking vodka (a beverage with a high ethanol content, for those of you unfamiliar with this substance) would be expected to cause excretion of a

A. large volume of concentrated urine
B. small volume of concentrated urine
C. large volume of dilute urine
D. small volume of dilute urine
E. normal volume of urine of normal osmolality

35. Drinking which of the following would lead to the highest rate of ADH secretion and release?

A. two liters of distilled water
B. two liters of sea water (mainly hyperosmotic saline)
C. two liters of iso-osmotic (isotonic) saline
D. two liters of human blood plasma
E. none of the above, since drinking two liters of any liquid leads to inhibition of ADH release

36. In a patient with severe renal artery stenosis (narrowing), all of the following would be expected to be increased above normal except

A. plasma renin concentration
B. plasma angiotensin II concentration
C. blood pressure (hydrostatic pressure) in the glomerular capillaries
D. resistance to blood flow in the efferent arteriole
E. systemic arterial blood pressure

37. Administration of an Angiotensin Converting Enzyme inhibitor (ACE inhibitor) to the above patient might lead to acute renal failure by

A. inhibiting renal tubule potassium reabsorption
B. increasing renal resistance to blood flow
C. causing plasma proteins to be excreted in the urine
D. causing systemic arterial hypertension
E. reducing glomerular filtration rate

38. Which of the following is the stimulus for increased secretion of atrial natriuretic peptide (ANP)?

A. increase blood plasma osmolality above normal
B. decrease blood plasma osmolality below normal
C. increase systemic arterial pressure
D. increase venous blood volume and atrial pressure
E. increase cardiac contractility (force of contraction)

39. An increase secretion of renin would be expected to have what effect on sodium excretion and potassium excretion in urine?

A. increase in Na+ excretion and increase K+ excretion
B. increase in Na+ excretion and decrease K+ excretion
C. decrease in Na+ excretion and increase K+ excretion
D. decrease in Na+ excretion and decrease K+ excretion
E. decrease in Na+ excretion but no effect on K+ excretion

40. In which of the following fluids is the pH highest (most alkaline)? (Assume the person is normal.)

A. systemic arterial blood plasma
B. systemic venous blood plasma
C. urine
D. all of the above, since pH is normally of the same for all
E. A and B above, since blood plasma pH is relatively uniform

41. The ammonium (NH4⁺) ion that may be present in urine is produced by

A. breakdown of urea in the liver
B. metabolism of amino acids in the renal tubule and collecting duct
C. aerobic carbohydrate metabolism
D. gylcolytic pathways during anaerobic metabolism
E. gluconeogensis during starvation

42. The reason that respiratory compensation for metabolic alkalosis can never be complete (return plasma pH to normal) is that (Note: PaCO₂ = systemic arterial carbon dioxide partial pressure.)

A. high PaCO₂ inhibits respiratory ventilation
B. high PaCO₂ stimulates respiratory ventilation
C. low PaCO₂ inhibits respiratory ventilation
D. low PaCO₂ stimulates respiratory ventilation
E. none of the above, since respiratory compensation for metabolic alkalosis can be complete

43. The appearance of large amounts of ammonium ion (NH4⁺) in the urine is characteristic of the renal response to

A. respiratory acidosis
B. respiratory alkalosis
C. acidosis resulting from pancreatic diabetes
D. alkalosis resulting from gastric vomiting
E. both A and C above

44. An individual hoping for an LSD "acid high" mistakenly gives himself an intravenous injection of hydrochloric acid. The responses of his body which attempt to compensate for this ignorance of physiology include all of the following except

A. hyperventilation
B. increase in the acid form of the blood fixed buffers
C. decrease in blood bicarbonate ion concentration
D. increase in urine bicarbonate ion excretion
E. increase in urine ammonium ion excretion

45. A systemic arterial blood sample taken from the above individual an hour after his HCl "adventure" might show which of the following?

A. base excess = +10 meq/liter; PaCO₂ = 50 mmHg
B. base excess = +10 meq/liter; PaCO₂ = 30 mmHg
C. base excess = -10 meq/liter; PaCO₂ = 50 mmHg
D. base excess = -10 meq/liter; PaCO₂ = 30 mmHg
E. base excess = 0 meq/liter; PaCO₂ = 40 mmHg

46.  A young woman is found comatose, having taken an unknown number of sleeping pills an unknown time before. An arterial blood sample yields the following values:

pH      7.02
HCO₃^-   14 meq/liter
PaCO₂   68 mmHg

This patient's acid-base status is most accurately described as

A. uncompensated metabolic acidosis
B. uncompensated respiratory acidosis
C. simultaneous respiratory and metabolic acidosis
D. respiratory acidosis with partial renal compensation
E. respiratory acidosis with complete renal compensation

Question

Regarding the regulation of plasma sodium:

a) The granular cells of the afferent arterioles cells secrete renin when plasma sodium is low.

b) Angiotensin II is formed from renin by the action of an enzyme found on the endothelium of the pulmonary blood vessels.

c) The uptake of sodium ions is regulated by the proximal tubule.

d) Sodium transport by the thick ascending limb of the loop of Henle occurs by the same mechanism as that of the proximal tubule.