Final answer:
The kidneys regulate the volume and composition of body fluids, maintaining homeostasis by controlling osmolarity, electrolytes, and pH balance.
Step-by-step explanation:
The primary function of the kidneys involves regulating the volume and the composition of plasma and interstitial fluid. The kidneys are critical in maintaining homeostasis by filtering the blood, excreting waste, and balancing electrolytes, pH, and fluid volume. They play a key role in homeostasis by regulating the balance of minerals, such as sodium, potassium, and calcium, and by controlling blood pressure and red blood cell production through hormone secretion.
By adjusting the excretion or retention of water and various ions, the kidneys control the osmolarity of bodily fluids and regulate the acid-base balance to maintain a stable internal environment. For example, they regulate the concentration of bicarbonate in urine to balance pH levels and directly impact blood pressure through regulation of extracellular fluid volume including salt and water retention or loss.