Which structure is primarily responsible for the bulk reabsorption of glucose and amino acids in the nephron?

The proximal convoluted tubule is the primary site for the bulk reabsorption of glucose and amino acids in the nephron. This segment of the nephron is lined with specialized epithelial cells that contain numerous microvilli, significantly increasing the surface area for absorption.

In this region, glucose and amino acids are reabsorbed through active transport mechanisms, which often involve co-transport proteins. For instance, sodium-glucose co-transporters facilitate the uptake of glucose alongside sodium ions from the tubular fluid into the cells of the proximal convoluted tubule. Once inside the cells, glucose can then be transported into the interstitial fluid and subsequently re-enter the bloodstream.

Additionally, a similar process occurs for amino acids, where specific amino acid transporters facilitate their uptake. This efficient reabsorption process ensures that these crucial nutrients are retained in the body rather than being lost in urine.

In contrast, the distal convoluted tubule, collecting duct, and Loop of Henle primarily handle different functions, such as salt and water reabsorption and the concentration of urine. Thus, they do not play a significant role in the reabsorption of glucose and amino acids, which is why the proximal convoluted tubule is correctly identified as the site of