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The impulse which generated in SA node s...

The impulse which generated in SA node suddenly fails to be transmitted in both ventricles than –

A

Only atria contract, ventricles not contract

B

Only ventricles contract

C

Atria and ventricles contract at different rate

D

The whole heart stop contraction

Text Solution

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The correct Answer is:
To solve the question regarding the failure of impulse transmission from the SA node to both ventricles, we can break it down step by step: ### Step-by-Step Solution: 1. **Understanding the Role of the SA Node**: - The Sinoatrial (SA) node, located in the right atrium, is known as the natural pacemaker of the heart. It generates electrical impulses that initiate the heartbeat and regulate the heart rate. 2. **Implications of Impulse Failure**: - If the impulse generated by the SA node fails to be transmitted to the ventricles, it means that the normal electrical conduction pathway is disrupted. This affects how the heart chambers contract. 3. **Contraction of Atria and Ventricles**: - Normally, the SA node sends signals that cause the atria to contract first, pushing blood into the ventricles. Following this, the ventricles contract to pump blood to the lungs and the rest of the body. - If the impulse fails to reach the ventricles, the atria may still contract, but the ventricles will not receive the signal to contract in sync. 4. **Resulting Heart Activity**: - In this scenario, the atria may contract independently, but the ventricles will not contract at the same time or may not contract at all. This leads to a situation where the contraction rates of the atria and ventricles differ significantly. 5. **Evaluating the Options**: - **Option 1**: Only the atria contract and the ventricles do not contract - This is incorrect as the atria may contract, but the ventricles will not contract in sync. - **Option 2**: Only the ventricles contract - This is incorrect as the ventricles are not receiving the impulse. - **Option 3**: The ventricles contract at a different rate - This is correct because the atria may still contract while the ventricles do not receive the impulse to contract normally. - **Option 4**: The whole heart stops contracting - This is incorrect as the atria can still contract. 6. **Conclusion**: - The correct answer is that the ventricles contract at a different rate due to the failure of impulse transmission from the SA node. ### Final Answer: The correct option is that the ventricles contract at a different rate. ---
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