AP BIOLOGY

Detailed explanation-1: -It regulates pH by absorbing bicarbonate and secreting protons (H+) into the filtrate, or by absorbing protons and secreting bicarbonate into the filtrate. Sodium and potassium levels are controlled by secreting K+ and absorbing Na+. Sodium absorption by the distal tubule is mediated by the hormone aldosterone.

Detailed explanation-2: -The distal convoluted tubule (DCT) is a short nephron segment, interposed between the macula densa and collecting duct. Even though it is short, it plays a key role in regulating extracellular fluid volume and electrolyte homeostasis.

Detailed explanation-3: -The proximal tubule, the first segment to come into contact with the forming urine, plays an important role in helping the kidneys to maintain pH homeostasis.

Detailed explanation-4: -Intercalated cells are epithelial cells traditionally associated with the regulation of acid-base homeostasis in distal segments of the kidney tubule (Figure 1) (1). These cells also participate in potassium and ammonia transport and have a role in the innate immune system.