ANATOMY

Detailed explanation-1: -After reabsorption of K+ along the proximal tubule and loop of Henle, approximately 10% of filtered K+ reaches the DCT. As fluid travels down the DCT, the luminal potassium concentration increases, indicating that net K+ secretion occurs along the distal tubule.

Detailed explanation-2: -This reabsorption occurs in the PCT, loop of Henle, DCT, and the collecting ducts while the majority of secretion occurs in the PCT and DCT (Table 25.5 and Figure 25.5.

Detailed explanation-3: -The distal convoluted tubule also contains intercalated (I) cells, responsible for the secretion of acid. The collecting ducts are composed of I cells and also principal (P) cells, which become permeable to water under the influence of vasopressin.

Detailed explanation-4: -So, tubular secretion in nephron occurs in PCT and henle’s loop.

Detailed explanation-5: -Early Distal Convoluted Tubule It is impermeable to water. Movement of these ions is dependent on the Na+/K+-ATPase transporter on the basolateral membrane of the cells. This excretes sodium ions into the extracellular fluid, and brings potassium ions into the cell.