Final answer:
The process by which the kidneys return fluid from the tubules into the bloodstream is termed reabsorption, primarily occurring in the proximal convoluted tubule and loop of Henle, controlled by hormones, and involving the recovery of solutes and water.
Step-by-step explanation:
The process whereby fluid in the kidneys is transported from the tubules back into the bloodstream is known as reabsorption. This biological function is a crucial step in urine formation where solutes and water are reclaimed after initial filtration. During this process, substances like glucose, amino acids, and salts are moved from the filtrate found in the renal tubules back into the peritubular capillaries of the glomerulus, primarily occurring in the proximal convoluted tubule and the loop of Henle.
By the time the filtrate reaches the distal convoluted tubule (DCT), a significant amount of solutes and water has been reabsorbed into the bloodstream. At this stage, if the body needs additional water, reabsorption can increase. This stage is regulated by hormones, determining the amount of water and solutes returned to the bloodstream. The remaining unabsorbed waste is ultimately excreted as urine, mainly via tubular secretion which occurs later in the DCT and the initial part of the collecting duct.
The correct term for the transfer of fluid from kidney tubules back to the bloodstream is reabsorption.