Question

Differentiate between the Following:

Reabsorption and Secretion

Answer 1

Basis of Difference	Reabsorption	Secretion
Meaning	Reabsorption is the return of useful substances from the glomerular filtrate to the blood.	Secretion is the movement of certain substances from the blood into the renal tubule.
Direction of movement	Substances move from the renal tubule into the surrounding blood capillaries.	Substances move from the blood capillaries into the renal tubule.
Substances involved	Water, glucose, amino acids and useful salts are selectively reabsorbed.	Hydrogen ions, potassium ions, ammonia, drugs and toxins may be secreted.
Main site	Reabsorption occurs mainly in the renal tubules, especially the PCT.	Tubular secretion occurs mainly in the distal convoluted tubule.
Importance	It prevents the loss of useful substances and helps maintain fluid balance.	It removes additional wastes and helps maintain the normal salt and acid-base balance.