3.6 Control of heart rate

Question 1

Where is the sinoatrial node (SAN) located ?

Answer 1

It is located in the right atrium

Question 2

Where is the atrioventricular node (AVN) located ?

Answer 2

It is located near the border of the right atrium and ventricle

Question 3

Where is the bundle of his located ?

Answer 3

At the septum (bottom) of the heart

Question 4

Where are the purkyne fibres located ?

Answer 4

In the walls of the ventricles

Question 5

How many times a min does the SAN send out a wave ?

Answer 5

55-80 times a minute

Question 6

Outline the process of the cardiac cycle

Answer 6

1- SAN sends out a wave of excitation
2- The atria contract
3- AVN delays impulse for 0.1 seconds to allow atria to continue contraction
4- AVN sends a wave of excitation
5- Purkyne tissues conduct wave of excitation
6- This stimulates ventricle to contract

Question 7

What neurotransmitter is released after the chemoreceptors detect high levels of O2/low levels of CO2?

Answer 7

Acetylcholine