How a heart beat is initiated:
· Heart is myogenic
· SAN is the hearts pacemaker, it initiates its own action potential which travels as a wave of excitation over the atria walls.
· It reaches the AVN and travels down the Purkyne tissue, into the ventricles causing them to contract.
· The heart is supplied by nerves from the medulla oblongata, which are connected to the SAN. This controls the frequency of contraction.
How the heart rate is increased:
· Increased activity is detected by stretch receptors…