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A : The cardiac impulse which originates...

A : The cardiac impulse which originates from SA node in mammalian heart cannot spread directly from atria to ventricles
R : In mammalian heart there is no continuity between cardiac muscle fibres of atria and those of ventricles except AV bundles.

A

If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion.

B

If both Assertion and Reason are true, but the Reason is not the correct explanation of the Assertion.

C

If Assertion is true, but Reason is false.

D

If both Assertion and Reason are false.

Text Solution

AI Generated Solution

The correct Answer is:
To solve the question, we need to analyze both the assertion and the reason provided. ### Step-by-Step Solution: 1. **Understanding the Assertion**: - The assertion states that the cardiac impulse originating from the SA node in the mammalian heart cannot spread directly from the atria to the ventricles. - This is true because the SA node (sinoatrial node) initiates the heartbeat, but the impulse must travel through specific pathways to reach the ventricles. 2. **Understanding the Reason**: - The reason given is that in the mammalian heart, there is no continuity between the cardiac muscle fibers of the atria and those of the ventricles, except for the AV bundles (atrioventricular bundles). - This statement is also true. The atria and ventricles are separated by a fibrous skeleton that prevents direct electrical conduction between them. 3. **Connection Between Assertion and Reason**: - The assertion is true because the impulse cannot spread directly due to the separation of muscle fibers. - The reason explains why the assertion is true: the absence of direct continuity between the atrial and ventricular muscle fibers necessitates the use of the AV node and the bundle of His for conduction. 4. **Conclusion**: - Both the assertion and the reason are true, and the reason correctly explains the assertion. Therefore, the correct option is that both the assertion and reason are true, and the reason is the correct explanation of the assertion. ### Final Answer: Both the assertion and reason are true, and the reason is the correct explanation of the assertion. ---
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Assertion : The AV bundle is essential for the conduction of cardiac impulse. Reason: There is no continuity between the cardiac muscle fibers of the auricles and those of the ventricles.

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Knowledge Check

  • The problem of electrical discontinuity caused in the normal heart by the connective tissue separating the atria from the ventricles is solved by

    A
    coordinating electrical activity in the atria with electrical activity in the ventricles by connecting them via the bundle of His
    B
    having the A-V node function as a secondary pacemaker
    C
    having an ectopic pacemaker
    D
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    A
    (i) and (ii)
    B
    (i) and (iii)
    C
    (ii),(iv) and (v)
    D
    all of these

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