MICROANATOMY

Detailed explanation-1: -As fluid travels down the DCT, the luminal potassium concentration increases, indicating that net K+ secretion occurs along the distal tubule. In the early DCT, the rate of K+ secretion is low, but it increases significantly in the late DCT (68–70).

Detailed explanation-2: -Potassium is secreted along the initial and cortical collecting tubule. Net secretion can be replaced by net reabsorption in states of potassium depletion. Also shown are the two cell types lining the distal tubule and cortical collecting duct.

Detailed explanation-3: -Potassium is freely filtered at the glomerulus and passes through to the proximal convoluted tubule (PCT) and loop of Henle, where most of it is reabsorbed. There is some reabsorption in the distal convoluted tubule and collecting duct, but potassium secretion also occurs at these sites.

Detailed explanation-4: -Potassium is freely filtered by the glomerulus. The bulk of filtered K+ is reabsorbed in the proximal tubule and loop of Henle, such that less than 10% of the filtered load reaches the distal nephron.