Venous valves are responsible for

Options

A. preventing anterograde flow.
B. channeling blood away from the heart.
C. channeling blood toward the heart.
D. preventing blood from re-entering a ventricle.

Answer

### Step-by-Step Solution:

1. **Understanding Venous Structure**:
- Veins have thinner walls compared to arteries, which is important because they operate under lower blood pressure.

2. **Function of Venous Valves**:
- The primary function of venous valves is to prevent the backflow of blood. This is crucial because veins carry blood back to the heart, and without valves, gravity could cause blood to flow backward, especially in the limbs.

3. **Unidirectional Blood Flow**:
- The presence of these valves ensures that blood moves in a unidirectional manner, meaning it flows only towards the heart and not in the opposite direction.

4. **Definition of Anterograde Flow**:
- Anterograde flow refers to the forward movement of blood towards the heart. The valves facilitate this by closing when blood attempts to flow backward, thus maintaining this one-way flow.

5. **Conclusion**:
- Therefore, the venous valves are responsible for preventing backflow of blood, ensuring that blood flows in a single direction (anterograde) towards the heart.

### Final Answer:
Venous valves are responsible for preventing the backflow of blood, ensuring unidirectional flow towards the heart.

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