Glomerular filtration rate is

Options

A. amount of blood filtered by kidneys in an hour
B. amount of filtrate formed by kidneys per minute
C. only decreased by action of JGA
D. about 125 L/minute

Answer

**Step-by-Step Solution:**

1. **Understanding Glomerular Filtration Rate (GFR):**
- GFR is a measure of how well the kidneys are filtering blood. It specifically refers to the volume of blood that is filtered by the glomeruli (the filtering units of the kidney) per unit of time.

2. **Location of Filtration:**
- The filtration occurs in the glomerulus, which is part of the nephron (the functional unit of the kidney). The glomerulus is also referred to as the Malpighian body.

3. **Normal Range of GFR:**
- In healthy individuals, the normal GFR is typically between 90 to 120 milliliters per minute (ml/min). This indicates the efficiency of the kidneys in filtering blood.

4. **Evaluating Options:**
- **Option 1:** "The amount of blood filtered by the kidney in an hour."
- This is incorrect because GFR is measured per minute, not per hour.
- **Option 2:** "The amount of filtrate formed by the kidney per minute."
- This is correct as it accurately describes GFR.
- **Option 3:** "Only decreased by the action of JGA (Juxtaglomerular Apparatus)."
- This is incorrect; the JGA can help regulate and maintain GFR, not just decrease it.
- **Option 4:** "About 125 liters per minute."
- This is incorrect as it greatly exceeds the normal range of 90 to 120 ml/min.

5. **Conclusion:**
- The correct answer is the second option, which states that GFR is "the amount of filtrate formed by the kidney per minute."