Question

The part of nephron involved in active reabsorption of sodium is

• A. descending limb of Henle's loop
• B. distal convoluted tubule
• C. proximal convoluted tubule
• D. Bowman's capsule

Answer 1

The correct option is C proximal convoluted tubule

Steps in urine formation:

• Ultrafiltration
• Selective reabsorption
• Tubular secretion

Bowman’s capsule is a cup-like structure that encloses a network of blood capillaries, the glomerulus. The blood from glomerular blood capillaries gets filtered into the Bowman's cup.

The glomerular filtrate has several essential substances along with enormous amounts of water that get reabsorbed in various parts of the nephron.

Reabsorption is necessary to prevent loss of essential nutrients in urine.

Around 99 percent of filtrate formed is reabsorbed. Reabsorption can take place in different segments of nephron.

Nearly all of the essential nutrients, and 70-80 percent of electrolytes and water are reabsorbed by proximal convoluted tubule (PCT). PCT is the highly coiled structure found next to Bowman’s capsule.

The epithelial cells of renal tubule reabsorb these substances either by active or passive mechanisms. Substances like glucose, amino acids, Na+, are reabsorbed by active transport. Substances like nitrogenous wastes and water are reabsorbed passively.

The tubular cells secrete H+, K + and ammonia into the filtrate, this is called tubular secretion. Tubular secretion helps in the maintenance of ionic and acid base balance of body fluids.

Hence, option C is the correct answer.