Myogenic Stimulation of the Heart (AQA A Level Biology): Revision Note
Exam code: 7402
Myogenic stimulation of the heart
The contraction of heart muscle is myogenic; this means that the heart beats at a baseline rate without any input from the nervous system
Thy myogenic control of the heart beat involves the:
sinoatrial node (SAN): a group of cells in the wall of the right atrium, often referred to as the pacemaker
atrioventricular node (AVN): conductive tissue that links the atria and ventricles
bundle of His: conductive fibres that carry waves of depolarisation down the septum to the base of the ventricles
Purkyne tissue: conductive fibres that carry waves of depolarisation from the base of the ventricles into the ventricle walls
The sequence of events during which the heart beat is initiated and controlled is as follows:
Event | Effect on heart |
|---|---|
The SAN initiates a wave of depolarisation which passes across the atria | The atria contract |
The wave of depolarisation reaches non-conducting tissue that separates the atria and ventricles, before it passes to the AVN | There is a delay which allows the atria to empty into the ventricles before ventricular contraction begins |
Electrical activity passes from the bundle of His to the Purkyne tissue | The ventricles contract from the base upwards |
Examiner Tips and Tricks
Make sure that you don't confuse the SAN and the AVN:
The SAN initiates the heart beat
The AVN conducts electrical activity from the atria to the ventricles
Unlock more, it's free!
Did this page help you?
