MCAT Question A Day - 7/30/14 - Answer!
The epithelial cells of the proximal convoluted tubule contain a brush border similar to the brush border of the small intestine. The most likely function of the brush border in the proximal convoluted tubule is to:
A. increase the amount of filtrate that reaches the loop of Henle.
B. increase the surface area available for the absorption.
C. slow the rate of at which the filtrate moves through the nephron.
D. move the filtrate through the nephron with cilia like action.
B is correct. The purpose of the brush border is to increase the surface area available to reabsorb solutes from the filtrate. The brush border is made from villi, not cilia, and so has little or no bearing on the direction or rate of fluid movement.
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B is correct. The purpose of the brush border is to increase the surface area available to reabsorb solutes from the filtrate. The brush border is made from villi, not cilia, and so has little or no bearing on the direction or rate of fluid movement.
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