The proximal convoluted tubule is the tubular segment of the nephron that connects the renal corpuscle to the proximal straight tubule and ultimately to the loop of Henle. It is located in the renal cortex of the medulla and functions in both reabsorption and secretion. In fact, this is where the majority of the reabsorption of electrolytes and water takes place. Approximately two-thirds of the sodium ions and water and one-hundred percent of the glucose and amino acids is reabsorbed in the proximal convoluted tubule. The reason that so much absorption takes place within this section of the nephron is due to the presence of the brush border (microvili) on the epithelial cells. The brush border greatly increases the surface area and allows the membrane proteins to absorb and secrete the different types of molecules very efficiently. The proximal convoluted tubule also secretes things such as hydrogen ions and bicarbonate molecules. This allows the nephron to regulate the pH of the blood plasma.
Sorgente: AK LECTURES – Proximal Convoluted Tubule