ANATOMY

Detailed explanation-1: -This is another important route for reabsorption of small solutes such as sodium chloride, and of water. Sodium continues to be reabsorbed in this part of the tubule via sodium/proton exchangers and actively transported through the tubule wall to the bloodstream by the sodium/potassium ATPase.

Detailed explanation-2: -in which direction do substances move during tubular reabsorption? from the tubular fluid into the blood.

Detailed explanation-3: -Water reabsorption is by osmosis through water channels in the membrane. These water channels consist of a family of proteins called aquaporin. At least seven different aquaporin isoforms are expressed in the kidney.

Detailed explanation-4: -Tubular secretion is the process by which solutes or other materials are transferred from the peritubular capillaries into the renal tubular lumen. Secretion involves the transfer of hydrogen ions, creatinine, drugs, and urea from the blood into the collecting duct of the nephron.

Detailed explanation-5: -Reabsorption is a finely tuned process that is altered to maintain homeostasis of blood volume, blood pressure, plasma osmolarity, and blood pH. Reabsorbed fluids, ions, and molecules are returned to the bloodstream through the peri-tubular capillaries, and are not excreted as urine.