A severe fall in blood pressure disturbs the function of kidneys and reduces

Options

A. Reabsorption of useful substances
B. Glomerular filtration
C. Secretion of nitrogenous waste
D. Renal filtration

Answer

**Step-by-Step Solution:**

1. **Understanding the Question:**
The question states that a severe fall in blood pressure affects kidney function and asks what specific process is reduced as a result.

2. **Identifying Key Terms:**
- Blood Pressure: The force exerted by circulating blood on the walls of blood vessels.
- Kidneys: Organs that filter blood, remove waste, and regulate fluid balance.
- Glomerular Filtration: The process by which the kidneys filter blood, removing excess waste and fluids.

3. **Analyzing the Options:**
- **A. Reabsorption of useful substances:** This process occurs after filtration, so it is not directly affected by blood pressure.
- **B. Glomerular filtration:** This is the process of filtering blood in the kidneys, which is directly influenced by blood pressure.
- **C. Secretion of nitrogenous waste:** This is a process that occurs after filtration and is not primarily affected by blood pressure.
- **D. Renal filtration:** This is a general term that can refer to glomerular filtration.

4. **Understanding the Mechanism:**
- Glomerular filtration rate (GFR) is dependent on the pressure gradient in the glomerulus. A fall in blood pressure leads to decreased pressure in the glomeruli, resulting in reduced GFR.
- When blood pressure is low, the afferent arterioles (bringing blood into the glomerulus) constrict, and the efferent arterioles (taking blood out of the glomerulus) dilate, which lowers the GFR.

5. **Conclusion:**
The correct answer is **B. Glomerular filtration**. A severe fall in blood pressure reduces the glomerular filtration rate, affecting the kidneys' ability to filter blood effectively.

---