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

Options

(a) Descending limb of Loop of Henle is impermeable to water
(b) Distal convoluted tubule is incapable of reabsorbing HCO₃
(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

Correct Answer:

Nearly 99 per cent of the glomerular filtrate is reabsorbed by the renal tubules

Explanation:

Urine formation involves three main process called, glomerular filtration, reabsorption and secretion. A comparison of the volume of the filtrate formed per day (which is 180 litres per day) will that of urine released (about 1.5 litres) suggest that nearly 99 percent of the glomerular filtrate is resorbed by the renal tubules. The descending limb of the loop of Henle is permeable to water but impermeable to electrolytes. The ascending limb is impermeable to water but allows transport of electrolytes. Reabsorption of sodium ions and water takes place in the distal convoluted tubule. Also, it is capable of reabsorption of HCO₃.