6- ♥ rate =)

Question 1

Describe the route taken when electrical impulses are transmitted from the sinoatrial node to the muscles of the ventricles in a healthy heart. (2)

Answer 1

• thru cardiac mucle
• to AVN along bundle of His/ Purkyne fibres

Question 2

Exercise causes an increase in heart rate.
Describe the role of receptors and of the nervous system in this process. (4)

Answer 2

• chemoreceptors detect ↓ pH
• impulses to medulla
• ↑ impulses to SAN
• along synpathetic nerve

Question 3

A Level-

Caffeine affects the autonomic nervous system.
Suggest how caffeine could account for the increase in heart rate 60 after intake. (2)

Answer 3

• more impulses along the symphatic nervous system pathway
• to the SAN (sinoatrial node) to increase heart rate