Assertion -SA node induces excitatory impulses in heart- Reason- SA node is self excitatory-Both Assertion and Reason are correct and Reason is the correct explanation for Assertion-Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion-Assertion is correct but Reason is incorrect-Both Assertion and Reason are incorrect-

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Byju's Answer

Standard VIII

Biology

Animal Tissues

Assertion :SA...

Question

Assertion :SA node induces excitatory impulses in heart. Reason: SA node is self excitatory.

Both Assertion and Reason are correct and Reason is the correct explanation for Assertion.

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Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion.

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Assertion is correct but Reason is incorrect.

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Both Assertion and Reason are incorrect.

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Solution

The correct option is A Both Assertion and Reason are correct and Reason is the correct explanation for Assertion.
Sinu-auricular node or SA node is located in the wall of the right auricle below the opening of the superior vena cava. The SA node has unique property of self excitation, which enables it to act the 'pacemaker' of the heart. It spontaneously initiates a wave of contraction which spreads over both the auricles more or less spontaneously along the muscle fibres that fan out from the pacemaker.

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Similar questions

Q. Given below are assertion and reason. Point out if both are true with reason being correct explanation (A), both are true but reason is not correct explanation (B), assertion is true but reason is wrong (C), and both are wrong (D).
Assertion. SA node produces excitatory impulses in heart
Reason. SA node is self excitatory.

Q. Assertion: SA node induces excitatory impulses in the heart.
Reason: S.A. node is self-excitatory.

Q. Assertion: The compressibility factor for

H_{2}

and

H e

(1 + \frac{P b}{R T})

Reason: The compressibility factor for

H_{2}

and

H e

can be derived from Van der Waal's equation.

Assertion (A) Order of the reaction can be zero or fractional.

Reason (R) We cannot determine order from balanced chemical equation.

(a) Both assertion and reason are correct and the reason is correct explanation of assertion
(b) Both assertion and reason are correct, but reason does not explain assertion.
(c) Assertion is correct, but reason is incorrect
(d) Both assertion and reason are incorrect
(e) Assertion is incorrect but reason is correct.

Assertion (A) Order and molecularity are same.

Reason (R) Order is determined experimentally and molecularity is the sum of the stoichimetric coeffcient of rate determining elementary step.

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