Question

Which one of the following statements in regard to the excretion by the human kidneys is correct?

• A. descending limb of loop of Henle is impermeable to water
• B. distal convoluted tubule is incapable of reabsorbing $HC{O}_3$
• C. nearly 99 per cent of the glomerular filtrate is reabsorbed by the renal tubules
• D. ascending limb of loop of Henle is impermeable to electrolytes.

Answer 1

Answer: (C)

Urine formation involves three main processes namely, glomerular filtration, reabsorption and secretion, that takes place in different parts of the nephron. A comparison of the volume of the filtrate formed per day (180 litres per day) with that of the urine released (1.5 litres), suggest that nearly 99 percent of the filtrate is reabsorbed by the renal tubules. The descending limb of loop of Henle is permeable to water but almost impermeable to electrolytes. The ascending limb is impermeable to water but allows transport of electrolytes actively or passively. Conditional reabsorption ofNa' and water takes place in distal convoluted tubule. It is also capable of reabsorption of HC0₃.