Question

Where does glucose reabsorption occur?

• A. In PCT
• B. In DCT
• C. In Henle's loop
• D. All of these

Hint:

If glucose appears in the urine, it is a key indicator of diabetes mellitus. This happens when blood glucose levels are so high that the PCT's reabsorption capacity is overwhelmed.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
The question is about the process of urine formation in the nephron, the functional unit of the kidney. After blood is filtered in the glomerulus, the resulting filtrate contains water, salts, glucose, amino acids, and urea. Essential substances like glucose need to be reabsorbed back into the blood.

Step 2: Detailed Explanation:
The nephron consists of several parts where reabsorption and secretion occur:
\[\begin{array}{rl} \bullet & \text{Proximal Convoluted Tubule (PCT): This is the first section after Bowman's capsule. It is the primary site for the reabsorption of most of the essential substances from the filtrate. Nearly 100% of glucose and amino acids, about 65% of water, and most of the salts are reabsorbed here via active transport and osmosis. } \\ \bullet & \text{Henle's loop: Primarily responsible for creating a salt concentration gradient in the medulla, which helps in reabsorbing water. } \\ \bullet & \text{Distal Convoluted Tubule (DCT): Involved in the conditional reabsorption of water and salts, often under hormonal control. } \\ \end{array}\] Since virtually all glucose is reabsorbed in the first part of the tubule, the PCT is the correct answer.

Step 3: Final Answer:
Glucose reabsorption primarily and almost completely occurs in the Proximal Convoluted Tubule (PCT).