What job do the kidneys for excretory system?

The kidneys play several vital roles in the excretory system, ensuring the elimination of waste products and maintaining the body's homeostatic balance:

1. Filtration of Blood: The kidneys filter waste products, excess water, and various substances from the bloodstream. Blood enters the kidneys through the renal arteries and passes through tiny filtering units called nephrons.

2. Formation of Urine: The filtered fluid from the blood is modified within the nephrons to form urine. This fluid is composed of waste products, such as nitrogenous compounds (urea and uric acid), electrolytes, and excess water.

3. Reabsorption: As urine flows through the nephrons, essential substances like glucose, amino acids, water, and electrolytes are selectively reabsorbed back into the bloodstream. This conserves vital nutrients and maintains proper hydration.

4. Secretion: The kidneys also actively secrete certain substances, including drugs, toxins, hydrogen ions, and creatinine, into the nephrons. This helps eliminate harmful substances and regulate blood pH.

5. Regulation of Blood Volume and Pressure: The kidneys play a crucial role in maintaining blood volume and blood pressure balance. By adjusting the amount of water reabsorbed, they influence the volume of blood circulating in the body and contribute to blood pressure regulation.

6. Regulation of Electrolyte Balance: The kidneys help maintain the proper balance of electrolytes in the body, including sodium, potassium, calcium, and phosphate. This is essential for various physiological processes, including nerve function, muscle contraction, and heartbeat regulation.

7. Regulation of Acid-Base Balance: The kidneys contribute to maintaining the body's pH level by regulating the excretion or reabsorption of hydrogen ions and bicarbonate ions. This ensures the proper acid-base balance necessary for optimal enzyme activity and cellular function.

Overall, the kidneys are essential for the regulation and elimination of waste products, ensuring the body's efficient functioning, and maintaining the overall homeostasis of the internal environment.