Paper 2 - Control of Heart Rate Flashcards
1
Q
Baroreceptors
A
Pressure receptors in the aorta and carotid arteries that detach high blood pressure.
- Impulses are sent to the medulla
- Sent to the parasympathetic neurones
- Acetylcholine is secreted
- ACh binds to receptions on the SAN
So heart rate slows down to reduce blood pressure back to normal
2
Q
Chemoreceptors
A
Chemical receptors in the aorta, carotid arteries and medulla that detect chemical changes in the blood
- Impukses are sent to the medulla
-Sent to sympathetic neurones
-Secretes noradrenaline
-Binds to receptors on the SAN
So heart rate increases to return oxygen, carbon dioxide and pH levels back to normal
3
Q
What is the meaning of myogenic?
A
When a muscles can contract and relax without receiving signals from nerves.
4
Q
Control of heartbeat
A
- SAN generates electrical impulse by sending out waves of depolarisation to atrial walls which contract
- Collagen between atria and ventricles prevents direct signal transmission
- Transmitted to AVN
- Electrical signal transmitted down bundle of His
- Delay = time for atria to empty before ventricles contract
- Signal transmitted by bundle of His → Purkinje fibres in ventricle walls → contract from bottom up
5
Q
Autonomic Nervous System - Sympathetic control
A
- Fall in blood pressure in aorta is detected by baroreceptors
- Impulses carried in sensory neurones to cardiac centre in medulla
- More frequent impulses along sympathetic nerves to SAN
- Noradrenaline released from sympathetic nerve endings onto SAN
- SAN increases its rate of activity = increase in HR & BP
6
Q
Autonomic Nervous System - Parasympathetic Control
A
- Increase in blood pressure in aorta detected by baroreceptors
- Impulses carried in sensory neurones to cardiac centre in medulla
- More frequent impulses along parasympathetic to SAN
- Acetylcholine released from parasympathetic nerve onto SAN
- SAN decreases its rate of activity = decrease in HR & BP
