Atrioventricular valves are opened due to

Options

A. Decreased pressure in aorta
B. Increased pressure in atria
C. Decreased pressure in ventricles
D. Increased pressure in ventricles

Answer

To answer the question "Atrioventricular valves are opened due to," we will analyze the functioning of the heart and the conditions under which the atrioventricular (AV) valves open.

### Step-by-Step Solution:

1. **Understanding Atrioventricular Valves**:
- The atrioventricular valves are located between the atria and the ventricles of the heart. There are two types: the tricuspid valve (right side) and the mitral valve (left side).

2. **Heart's Phases**:
- The heart goes through two main phases: diastole (relaxed state) and systole (contracted state). During diastole, both the atria and ventricles are relaxed, allowing blood to flow into the heart.

3. **Blood Flow Dynamics**:
- When the heart is in diastole, blood from the body returns to the right atrium and blood from the lungs returns to the left atrium. This causes an increase in pressure within the atria.

4. **Pressure Differences**:
- The pressure in the atria becomes higher than the pressure in the ventricles during this phase. The ventricles are still relaxed and have lower pressure.

5. **Opening of the Valves**:
- The increased pressure in the atria forces the atrioventricular valves to open, allowing blood to flow from the atria into the ventricles. This is a crucial step in the cardiac cycle as it fills the ventricles with blood.

6. **Conclusion**:
- Therefore, the atrioventricular valves open primarily due to the **increased pressure in the atria** compared to the pressure in the ventricles.

### Final Answer:
Atrioventricular valves are opened due to increased pressure in the atria.

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