Glomerular filtration rate (GFR) is :

Options

A. amount of filtrate reabsorbed at the collecting ducts
B. amount of filtrate formed in both kidneys each minute
C. rate of bladder filling
D. amount of blood delivered to the kidney each minute

Explanation

### Step-by-Step Text Solution:

1. **Understanding Glomerular Filtration Rate (GFR)**:
- GFR refers to the volume of filtrate that is formed by the kidneys each minute. It is a crucial measure of kidney function.

2. **Definition of GFR**:
- GFR is defined as the amount of filtrate produced by the glomeruli of both kidneys in one minute. This filtrate is the fluid that passes through the glomerular membrane, containing water, ions, and small molecules, but excluding larger molecules like proteins and blood cells.

3. **Normal Values of GFR**:
- The normal GFR values vary between genders:
- For males: 85 to 125 ml/min
- For females: 65 to 115 ml/min
- These values indicate the efficiency of the kidneys in filtering blood.

4. **Elimination of Incorrect Options**:
- The other options provided in the question are incorrect:
- "Amount of the filtrate we absorb at the collecting duct" refers to reabsorption, not filtration.
- "Rate of the bladder filling" is unrelated to GFR.
- "Amount of the blood delivered to the kidney each minute" is not the same as the filtrate produced.

5. **Conclusion**:
- Therefore, the correct answer to the question is that GFR is the "amount of filtrate formed in the kidneys each minute."