How is the cardiac cycle controlled?

AS Biology Unit 1 revision

HideShow resource information

The sinoatrial node (SAN) produces a wave of electrical activity which causes both atria to contract, followed by the ventricles. The SAN initiates the heartbeat.

1 of 7

A wave of electrical activity spreads out from the SAN across both atria, causing them to contract.

2 of 7

A layer of non-conductive tissue (the atrioventricular septum)  prevents the wave crossing the ventricles.

3 of 7

The wave of electrical activity is allowed to pass through a second group of cells called the atrioventricular node (AVN), which lies between the atria.

4 of 7

The AVN,after a short delay, conveys a wave of electrical activity between the ventricles along a series of specialised muscle fibres called the bundle of His.

5 of 7

The bundle of His conducts the wave through the AV septum to the base of the ventricles,where the bundle branches into smaller fibres.

6 of 7

The wave of electrical activity is released from these fibres, causing the ventricles to contract quickly at the same time, from the apex of the heart upwards.

7 of 7


No comments have yet been made

Similar Biology resources:

See all Biology resources »See all resources »