Osmosis video - Proximal convoluted tubule

The proximal convoluted tubule (PCT) is a segment of the renal tubule responsible for the reabsorption and secretion of various solutes and water. The PCT is located in the renal cortex, the outer part of the kidney, and is the first segment of the renal tubule, where it receives the filtrate from the renal corpuscle.

The main function of the PCT is to reabsorb water and solutes like sodium, which is continuously pumped into the interstitium to create a gradient that allows many other solutes and even water to be reabsorbed by tubule cells. Certain metabolic byproducts and medications are also secreted into the tubular fluid by the proximal convoluted tubule and excreted in urine.