Question:
All the components of the nodal tissue are autoexcitable. Why does the SA node act as the normal pacemakar?
All the components of the nodal tissue are autoexcitable. Why does the SA node act as the normal pacemakar?
Updated On: Mar 19, 2026
- SA node has the lowest rate of depolarisation.
- SA node is the only component to generate the threshold potential.
- Only SA node can convey the action potential to the other components.
- SA node has the highest rate of depolarisation.
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The Correct Option is D
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Answer (d) SA node has the highest rate of depolarisation.
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Ans: SA nodes can act as the normal pacemaker because it has the highest rate of depolarization. The change in the electrical potential across the cell membrane is called depolarization, which will eventually lead to generation of action potential. This action potential will cause the muscle to contract. Thus on depolarization heart muscles contract and therefore pumping of the blood. SA nodes have the highest depolarization rate because their cells have the ability to automaticity. This allows the cells to generate action potentials spontaneously. The SA nodes also have ion channels thus help the cells to reach the threshold much faster.
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