PRACTICE QUESTIONS

1. The bulk of filtered water is reabsorbed by which renal tubule segment?

a. Proximal tubule

b. Lhin limbs of Henle's loop

c. Thick ascending limb of Henle’s loop

d.

c. Inner medullary collecting duct

2. The kidney responds rapidly to changing water require­ments. The ability to alter quickly the rate of water excre­tion by greatly concentrating or diluting the urine is the result of several factors. Which of the following does not contribute to this ability?

a. Generation of hypertonic medullary interstitium

b. Countercurrent flow and differential salt and water permeabilities in the thin limbs of Henle’s loop

c. Dilution of the tubule fluid by the thick ascending limb and the distal convoluted tubule

d. Responsiveness of the collecting duct to antidiuretic hormone (ADH)

e. ADH-regulated countercurrent flow and enhanced water permeability in the vasa recta

4. In dehydration, ADH is released, which reduces water excretion by:

a. Enhancing water reabsorption in the proximal tubules by stimulating Na⁺,K⁺-ATPase.

b. Enhancing water reabsorption in the thick ascending Iimh by stimulating the insertion of water channels into the apical plasma membrane.

c. Enhancing water reabsorption in the collecting duct by stimulating Na⁺,K*-ATPase activity.

d. Enhancing water permeability in the collecting duct by stimulating the insertion of water channels into the apical plasma membrane.

e. Reducing the glomerular filtration rate by activation of tubuloglomerular feedback.

5. In clinical situations the excretion of dilute urine may be caused by all the following except:

a. Chronic renal disease

b. Glucocorticoid administration

c. ADH deficiency

d. Hypoadrenocorticism

e. Acute renal hypoperfusion