Which structure of the nephron is primarily involved in reabsorbing filtered glucose back into the body?

• A. Bowman's capsule
• B. Loop of Henle
• C. Proximal tubule
• D. Distal tubule

Answer: (C)

The main idea is that reclaiming glucose from the filtrate happens primarily in the proximal tubule. In this segment, glucose is reabsorbed back into the bloodstream via sodium-linked transporters (SGLT1 and SGLT2) that cotransport glucose with sodium from the tubular fluid into the tubular cells. The sodium gradient driving this transport is maintained by the Na+/K+ ATPase on the basolateral side, and glucose then exits the cells into the blood through GLUT transporters. This process reclaims most of the filtered glucose under normal conditions, so very little remains to be excreted.

Bowman's capsule is where filtration occurs, not reabsorption. The Loop of Henle mainly concentrates urine by reabsorbing water and various ions, not glucose. The distal tubule fine-tunes reabsorption and secretion under hormonal control, but glucose reabsorption is not its primary role.