Narrowing of which of the following heart valves would cause blood to accumulate in the left atrium ?

Options

A. Tricuspid valve
B. Aortic valve
C. Mitral valve
D. Pulmonic valve

Answer

To determine which heart valve's narrowing would cause blood to accumulate in the left atrium, we can follow these steps:

### Step-by-Step Solution:

1. **Understand Heart Anatomy and Blood Flow**:
- The heart has four chambers: the right atrium, right ventricle, left atrium, and left ventricle.
- Blood flows from the body into the right atrium via the superior and inferior vena cavae, then to the right ventricle through the tricuspid valve.

2. **Identify the Role of Heart Valves**:
- Heart valves prevent the backflow of blood. The tricuspid valve is between the right atrium and right ventricle, the pulmonary valve is between the right ventricle and pulmonary artery, the mitral valve (or bicuspid valve) is between the left atrium and left ventricle, and the aortic valve is between the left ventricle and aorta.

3. **Analyze Each Valve Option**:
- **Tricuspid Valve**: If narrowed, it would cause blood to accumulate in the right atrium, not the left atrium.
- **Aortic Valve**: If narrowed, it would cause blood to accumulate in the left ventricle, not the left atrium.
- **Mitral Valve**: If narrowed, it would prevent blood from flowing from the left atrium to the left ventricle, leading to accumulation in the left atrium. This is a potential correct answer.
- **Pulmonary Valve**: If narrowed, it would cause blood to accumulate in the right ventricle, not the left atrium.

4. **Conclusion**:
- The valve that, if narrowed, would cause blood to accumulate in the left atrium is the **mitral valve**.

### Final Answer:
The correct answer is the **mitral valve**.

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