Question : Sino-atrial node is called the pacemaker of our heart. Why

1.	Question : Sino-atrial node is called the pacemaker of our heart. Why ?
Answer» Solution :The nodal musculature has the ability to generate ACTION potentials without any external stimuli, i.e. it is autoexcitable. However the number of action potentials that could be generated ina minue vary at different parts of the nodal system. The SAN can generated the maximum number of action potentails. i.e. `70 - 75 "MIN"^(-1)` and is responsibke for intiating and MAINTAINING the rhythmic contractile activity of the heart. THEREFORE it is called pacemaker.

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