Question

The heart beat begins with the depolarisation of:-

1.Atrio ventricular node (AVN)
2 Bundle of His
3.Sino atrial node (SAN)
4. Purkinje fibres​

Answer 1

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Depolarization of cardiac myocytes causes contraction of the cells and thus heart contraction occurs. Depolarization first begins in the SA node, which is also called the cardiac pacemaker. SA node has automaticity. The resting membrane potential of SA node is less negative than that of other cardiac cells.

Answer 2

Depolarization of cardiac myocytes causes contraction of the cells and thus heart contraction occurs. Depolarization first begins in the SA node, which is also called the cardiac pacemaker. SA node has automaticity. The resting membrane potential of SA node is less negative than that of other cardiac cells.