Heart Conduction and Contraction

Blood travels through the heart twice before returning to the body The double circulatory system

External view of the heart superior vena cava pulmonary artery aorta pulmonary vein pulmonary vein coronary artery right atrium left ventricle inferior vena cava right ventricle

Heart Section

The heart contains autorhythmic cells because they are self-excitable The heart contains autorhythmic cells because they are self-excitable. They generate spontaneous electrical impulses. These cells act as a pacemaker, setting the rhythm for the heart.

1. Cardiac excitation begins at the sinoatrial node 1. Cardiac excitation begins at the sinoatrial node. This caused the atria muscles to contract.

2. This electrical signal propogates through the atria to the atrioventricular node.

3. From the AV node, the electrical signal is carries along the Atrioventricular bundle (bundle of His.)

4. The signal goes through the bundle of His through the septum to the apex.

5. Finally, the signal makes it to the Purkinje fibres which causes the ventricles to contract. The time between contraction of the atria and ventricles is 0.20 seconds!

Finish