Final answer:
The kidney's regulation of water and substances in the blood is an example of homeostasis, which is vital for maintaining stable internal conditions.
Step-by-step explanation:
The kidney's regulation of water and other important substances in blood is an example of homeostasis. This essential physiological process ensures the internal environment of the body remains stable despite external changes. The kidneys maintain homeostasis by controlling the amount of water, ions, and other substances in the blood. They perform several homeostatic functions, including acid-base balance, regulation of electrolyte concentrations, and blood volume and pressure regulation. The kidneys also produce hormones such as erythropoietin, which regulates red blood cell production, and renin, which contributes to blood pressure regulation. These hormones and processes collectively help to stabilize the body's internal conditions.