Aldosterone is a hydrocorticosteroid that enhances renal reabsorption of sodium and water molecules, and mainly acts on the kidneys to reabsorb sodium and water molecules. When the extracellular fluid volume decreases, it stimulates glomerular paraglomerular cells to secrete renin, which activates the renin-angiotensin-aldosterone system, and aldosterone secretion is increased, which leads to an increase in the reabsorption of sodium ions by the kidneys, which then causes an increase in the reabsorption of water, and an increase in the volume of extracellular fluid. When the extracellular fluid volume increases, aldosterone secretion decreases through the opposite mechanism mentioned above, the kidneys reabsorb fewer sodium ions and water, the extracellular fluid volume decreases, the blood sodium decreases, and the blood potassium increases can also stimulate the adrenal cortex to increase aldosterone secretion, so aldosterone has an important physiological significance in the maintenance of the balance of the human body’s water and salt metabolism.