It increases tubular reabsorption of water, it stimulates the secretion of aldosterone, and stimulates the sense of thirst. While the glomerular capillaries are filtering the plasma, the peritubular capillaries are engaged in tubular reabsorption. Water is reabsorbed by osmosis and carries other solutes along by solvent drag. The PCT reabsorbs a greater variety of chemicals than any other part of the nephron. Some pass through the cytoplasm of the cell via the transcellular route, while others slip between epithelial cells using a paracellular route Tubular Secretion Tubular secretion is a process in which the renal tubule extracts chemicals from the capillary blood and secretes them into the tubular fluid.
Tubular secretion serves the purposes of waste removal and acid-base balance.
The primary purpose of the nephron loop is to enable the collecting duct to concentrate the urine. A distinguishing feature of these parts of the renal tubule is that they are subject to hormonal control. Two facts enable the collecting duct to produce such hypertonic urine. The osmolarity of the cellular fluid is four times as high near the renal papilla as it is in the cortex. The medullary portion of the CD is permeable to water but not to NaCl.