Conducting system of the heart

CONDUCTION PATHWAY

1) 1% of the cardiac cells = conducting cells

2) Functions of conducting cells - generate AP/impulses - conduct AP
3) SA node acts as the pacemaker of the heart, determining the rhythm ofthe heart beat.

3)Pathway : SA node - AV node - bundle of His - bundle branches -Purkinjefibers.

4)Conduction pathway ensures the heart pumps in a synchronised,coordinated way. This co-ordination ensures that the atria beat as oneunit, as well as the ventricles.

5)Different parts will conduct at a different speed. - Purkinje fibers and bundle of His (4m/sec) -fastest - SA node (1m/sec) - Ventricular myocardium (0.3-0.5m/sec) - AV node (0.05m/sec)-slowestThis is to ensure that the AP is received at the same time in every partof the heart. This will then allows the heart to contract at the sametime.


Clinical relevance:

1) ventricular fibrillation - the heart beats in a non-coordinatedfashion

2) defibrillation - a method in which a shock is performed to a patientwith an irregular rhythm in hoping that the heart will stop for a whileand start to beat again in a more coordinated fashion.