Question

Match the following:

$\begin{array}{cc}\text{1. Proximal convoluted tubule}& \text{i) Filtrate is hypotonic as it moves}\\ \text{2. Descending arm of Henle’s loop}& \text{ii) Filtrate is isotonic as it passes}\\ \text{3. Ascending arm of Henle’s loop}& \text{iii) Filtrate is hypertonic as it moves}\end{array}$

• A. 1 - i; 2 - ii; 3 - iii
• B. 1 - ii; 2 - iii; 3 - i
• C. 1 - iii; 2 - ii; 3 - i
• D. 1 - i; 2 - iii; 3 - iii

Answer 1

The correct option is B 1 - ii; 2 - iii; 3 - i

Urine formation involves three processes - ultrafiltration, reabsorption and secretion. While filtration is carried out in glomerulus, reabsorption can take place in all different segments of nephron.

The glomerular filtrate moves to proximal convoluted tubule after filtration. Filtrate in proximal convoluted tubule is isotonic as it passes through the tubule.

The descending limb of Henle’s loop is permeable to water but impermeable to electrolytes. This makes the filtrate concentrated as it moves down the Henle’s loop. Hence, the filtrate is hypertonic as it moves down through the descending limb of Henle’s loop.

The ascending limb is impermeable to water but permeable to electrolytes. Hence, the filtrate gets diluted as it passes the ascending loop region. Here, the filtrate is hypotonic as it passes through the ascending limb of Henle's loop.