Describe how the rhythmicity of the heart is established and maintained with respect to the different stages in the cardiac cycle (6 marks)
The Sinoatrial Node (SAN) generates the wave of excitation/ Action potential (AP).
The AP spreads across the atrial walls, stimulating the myocardial cells to contract This initiates the atrial systole.
The AP is then transmitted to the Atrioventricular Node (AVN).
Here it is delayed.
Once Atrial systole has finished the AP is conducted down the purkinje fibres/ bundle of His.
when it reaches the apex/base of the Heart it spreads across the ventricular walls.
This stimulates the myocardial cells in this region to contract.
This initiates the ventricular systole.
HM
Related Biology A Level answers
All answers ▸What are the different stages of mitosis and what do they consist of?
What are the advantages of saltatory conduction?
Using knowledge of the pathogenicity of HIV, explain why it can't be transmitted through inanimate objects or hand shakes with an infected person.
Explain why blood transfusion from a recently recovered Ebola patient may be an effective treatment ? (3 marks)