Question

Explain the term 'selective reabsorption'.

Answer 1

• Reabsorption is the process that absorbs necessary nutrients from the glomerular filtrate into the blood.
• The glomerulus filters water and small solutes out of the bloodstream.
• The resulting filtrate contains waste, but also other substances the body needs like essential ions, glucose, salts, amino acids, and smaller proteins.
• As the dilute filtrate passes down the tubule, much of the water is reabsorbed together with the usable substances.
• For example, substances like glucose, amino acids, $Na+$ , and more., in the filtrate are reabsorbed actively whereas the nitrogenous wastes are absorbed by passive transport.
• Reabsorption of water also occurs passively in the initial segments of the nephron.
• But their reabsorption is only to the extent that the normal concentration of the blood is not disturbed.
• Thus, it is also called selective reabsorption.