Final answer:
Aldosterone, a steroid hormone, targets the principal cells of the kidney to regulate electrolyte balance by increasing sodium reabsorption and potassium secretion. This action is part of the renin-angiotensin-aldosterone system that responds to changes in blood volume and pressure.
Step-by-step explanation:
Aldosterone is a steroid hormone that plays a crucial role in regulating the balance of electrolytes, specifically sodium and potassium, by affecting their reabsorption and secretion in the kidneys. You asked which cells aldosterone binds to; it specifically targets the principal cells of the kidney. These cells are located in the kidney tubules, especially within the distal convoluted tubule and the collecting duct.
When aldosterone binds to its receptors in these cells, it prompts the cells to increase the reabsorption of sodium ions (Na+) from the filtrate back into the bloodstream. Alongside promoting sodium retention, aldosterone also enhances the secretion of potassium ions (K+) and hydrogen ions into the urine, which helps in maintaining electrolyte balance as well as blood pressure.
Aldosterone is part of the renin-angiotensin-aldosterone system (RAAS), which is activated in response to low blood volume or low blood pressure. Through a process that involves the kidneys, liver, and lungs, aldosterone is ultimately released from the adrenal cortex. Its primary mechanism of action is to increase Na+ reabsorption, which brings more water back into the bloodstream, thereby increasing blood volume and pressure.