Lecture 4.1: Cellular and Molecular Events in the Heart

Question 1

How is a Coordinated Heartbeat produced? (3 broad steps)

Answer 1

• Non-contractile nodal cells intrinsically initiate ion-dependent electrical
events at regular intervals (60-80 per minute)
• Ion-dependent electrical impulses propagate from the SA node to the AV
node, via the intraventricular septum to the cardiac apex to initiate contraction
of the contractile cardiomyocytes
• This spreads through the myocardium to produce a co-ordinated heartbeat