Control of heart rate

Question 1

myogenic meaning

Answer 1

• myogenic -> nervous stimulation originating in muscle tissue (rather than neurones)
• so heart able to generate own electrical impulse w/o needing stimulation from nerves

Question 2

Write a summary of how the cardiac cycle is controlled by the SAN and the AVN (6)

Answer 2

• SAN acts as a pacemaker and initiates heartbeat
• SAN send a wave of electrical impulse across atria causing them to contract
• non conductive tissue betw atria and ventricles prevent electrical impulses from reaching ventricles
• short delay at AVN allows atria to empty and ventricles to fill before contracting
• AVN sends wave of e- im[pulse down Bundle of His and up Purkyne fibres
• causing ventricles to contraction bottom upwards

Question 3

Where are the chemoreceptors and pressure receptors which are involved in controlling heart rate found?

Answer 3

In the aortic arch and the carotid artery