The kidneys not only remove the waste products from the blood but also play a very important role in maintaining

Options

A. Equilibrium of the body
B. Temperature of the body
C. Constant composition of the blood irrespective of the nature of the food or fluid intake
D. Blood pressure constant

Answer

**Step-by-Step Solution:**

1. **Understanding the Primary Function of Kidneys:**
- The primary function of the kidneys is to filter waste products from the blood, which includes urea, creatinine, and excess salts and water.

2. **Identifying Additional Roles of the Kidneys:**
- Besides waste removal, kidneys have several other important functions. One of the key roles is maintaining homeostasis in the body.

3. **Regulation of Blood Composition:**
- The kidneys help regulate the composition of blood by balancing electrolytes (such as sodium, potassium, and calcium) and maintaining the acid-base balance.

4. **Regulation of Blood Pressure:**
- The kidneys play a crucial role in regulating blood pressure through the renin-angiotensin-aldosterone system (RAAS). When blood pressure is low, the kidneys release the enzyme renin, which leads to a series of reactions that increase blood pressure.

5. **Hormonal Regulation:**
- The kidneys also produce hormones such as erythropoietin, which stimulates red blood cell production in the bone marrow, and calcitriol, which is the active form of vitamin D that helps regulate calcium levels in the body.

6. **Maintaining Fluid Balance:**
- The kidneys help maintain fluid balance by adjusting the volume of urine produced, depending on the body’s hydration status and fluid intake.

7. **Conclusion:**
- In summary, while the kidneys are primarily known for waste removal, they also play a vital role in regulating blood composition, blood pressure, hormone production, and fluid balance, thus maintaining overall homeostasis in the body.

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