Control of heart

·         SAN initiates heartbeat / acts as a pacemaker /  myogenic;

·         (SAN) sends wave of electrical activity / impulses  (across atria) causing atrial contraction;

·         AVN delays (electrical activity / impulses);

·         (Allowing) atria to empty before ventricles contract / ventricles to fill before they contract;

·         (AVN) sends wave of electrical activity / impulses

·         down Bundle of His / Purkyne fibres;

·         (Causing) ventricles to contract