Sodium reabsorption does not occur in which part of the nephron?

Sodium reabsorption is a crucial function of the nephron, impacting fluid and electrolyte balance in the body. The collecting duct is primarily involved in the final regulation of water and solute concentration, often influenced by hormones like aldosterone and antidiuretic hormone (ADH), which can enhance or dampen water reabsorption, rather than sodium reabsorption.

In the nephron, significant sodium reabsorption occurs in the proximal convoluted tubule, where approximately 65-70% of filtered sodium is reabsorbed through various transport mechanisms. The loop of Henle also plays a role in reabsorbing sodium, particularly in the thick ascending limb, which is impermeable to water but actively reabsorbs sodium, contributing to the urine concentration gradient. Similarly, the distal convoluted tubule is engaged in sodium reabsorption via specialized sodium-chloride symporters, modulated further by hormones.

Thus, while all other segments of the nephron are involved in sodium reabsorption to various extents, the collecting duct primarily regulates water reabsorption in response to hormonal signals and is less focused on sodium reabsorption itself, which clarifies why it is identified as the part of the nephron where sodium