Which of the folllowing structures prevents atrioventricular valves from reverting into atria during ventricular contraction?

Options

A. Chordae tendine
B. Purkinje fibers
C. Bundle of His
D. Columnae carnae

Answer

To solve the question of which structure prevents the atrioventricular (AV) valves from reverting into the atria during ventricular contraction, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Function of Atrioventricular Valves**:
- The atrioventricular valves (AV valves) consist of the mitral valve (left side) and the tricuspid valve (right side). Their primary function is to prevent the backflow of blood from the ventricles into the atria during ventricular contraction (systole).

2. **Identify Structures Associated with AV Valves**:
- The key structures that support the AV valves include:
- **Chordae Tendineae**: These are fibrous cords that connect the AV valves to the papillary muscles in the ventricles.
- **Papillary Muscles**: These muscles contract during ventricular contraction, pulling on the chordae tendineae to keep the valves closed.
- Other structures like the **Bundle of His** and **Purkinje fibers** are involved in electrical conduction but do not prevent backflow of blood.

3. **Evaluate the Options**:
- **Chordae Tendineae**: As mentioned, these structures anchor the AV valves and prevent them from inverting.
- **Purkinje Fibers**: These are responsible for conducting electrical impulses in the heart.
- **Bundle of His**: This structure also conducts electrical signals but does not prevent backflow.
- **Columnae Carneae**: These are muscular ridges in the ventricles that help prevent the walls from collapsing but do not directly prevent backflow of blood through the AV valves.

4. **Select the Correct Answer**:
- The structure that specifically prevents the AV valves from reverting into the atria during ventricular contraction is the **Chordae Tendineae**.

### Final Answer:
The correct answer is **Chordae Tendineae**.

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