Question

Conditional reabsorption of sodium and water takes place in

• A. Distal convoluted tubule
• B. Proximal convoluted tubule
• C. Henle’s loop
• D. Collecting duct

Answer 1

The correct option is A

Distal convoluted tubule

The correct option is A.
Explanation of the correct option:

1. The distal convoluted tubule is held for conditional salt and water reabsorption in this segment.
2. The bulk of solutes essential for normal physiological function, including amino acids, glucose, and salts, are absorbed by the tubule's proximal part.
3. Reabsorption can be active, as with glucose, amino acids, and peptides, or passive, as with water, chloride, and other ions.
4. The DCT, PCT, Henle's loop, and collecting ducts are where absorption, reabsorption, and filtration occur.
5. While the PCT absorbs 70-80% of the water, the remaining 15-20% is reabsorbed in the DCT.
6. DCT reabsorption with the help of the hormone aldosterone maintains sodium and water levels.

Explanations of the incorrect options:
Option B:

1. The convoluted region of the vertebrate nephron that lies between Bowman's capsule and the loop of Henle and is responsible for the resorption of sucrose, sodium, chloride, and water from the glomerular filtrate.
2. Because it is the only site of transport for these filtered solutes, the proximal tubule also completes the reabsorption of glucose, amino acids, and essential anions such as phosphate and citrate.

Option C:

1. The Henle's loop is a long U-shaped section of the tubule that conducts urine through each nephron of a reptile, bird, or mammal's kidney.
2. The primary goal of Henle's loop is to recover water and sodium chloride from urine.
3. Henle's loop descends from the renal cortex and loops back up into the cortex.
4. This function enables the creation of urine that is significantly more concentrated than blood, hence reducing the amount of water required for living.

Option D:

1. The kidney's collecting duct system is made up of tubules and ducts that physically connect nephrons to a minor calyx or directly to the renal pelvis.
2. The final section of a long, twisting tube collects urine from the nephrons (cell structures in the kidney that filter blood and create urine) and transports it to the renal pelvis and ureters, also known as the renal collecting tubule.

Final answer: Conditional reabsorption of sodium and water takes place in the distal convoluted tubule.