Biology 3.1.2 Control of the cardiac cycle

Question	Answer
The cardiac muscle automatically contracts and relaxes without nerve stimulation, so it is described as...?	Myogenic
What initiates the cardiac cycle?	Sino-atrial node (SAN)
Where is the SAN located?	Walls of right atrium
What prevents the electrical wave passing to the ventricles as well the atria?	A band of collagen fibres between the aorta and ventricles
How does the electrical impulse get to the ventricles?	Through the AVN but it delays the wave so that blood can get into the ventricles before they contract
What is the pathway of the electrical impulse?	SAN AVN Purkyne fibres Bundle of his
What do the purkyne fibres do?	Conducts electrical impulses up and outwards through the ventricle walls
What factors can effect heart rate?	Age Fitness level Medical conditions Diet

Resource summary

	Created by Sam Gunnell over 5 years ago