A major fraction of filtered potassium is absorbed in:: (A) Collecting duct, (B) Distal convoluted tubule, (C) Proximal convoluted tubule, (D) Thick ascending limb of loop of Henle
Answer is C. Potassium is filtered at the glomerulus, reabsorbed & secreted by tubules, and is excreted in urine. Of the total K+ ingested in the diet, 90-95% is excreted. PCT :reabsorbs about 67% of the filtered K+ under most conditions; 20% of the filtered K+ is reabsorbed by the LOH. The two most impoant physiologic regulators of K+ secretion Plasma Aldosterone. Other factors include a Flow rate of the tubular fluid, acid-base balance, glucocoicoids.