Neural Control of Peripheral Circulation

Question 1

what is the general mechanism of feedback regulation?
- positive and negative

Answer 1

Question 2

what are the main blood pressure control mechanisms? (4)

Answer 2

1. arterial baroreceptors
2. parasympathetic efferents (ACh)
3. sympathetic efferents (NE - alpha1)
4. sympathetic efferents (NE - beta1)

Question 3

what is the feedback regulation by baroreceptor reflex?
parasympathetic

Answer 3

1. change (increase) in blood pressure
2. carotid and aortic baroreceptors increase stretch
3. sensory neurons sense the increase of stretch so they increase the firing of APs
4. signal to the medulla to increase neurotransmitter release
5. release of parasympathetic neurons only to SA node
6. this slow SA node firing, dilate arteries, decrease resistance and decrease BP
   ***end result changes to blood pressure feedback to the brain to increase to decrease

Question 4

what is the feedback regulation by baroreceptor reflex?
sympathetic

Answer 4

1. change (decrease) in blood pressure
2. carotid and aortic baroreceptors decrease stretch
3. sensory neurons sense the decrease of stretch so they increase the firing of APs
4. signal to the medulla to increase neurotransmitter (NE) release
5. release of sympathetic neurons to:
   - SA node = open Ca channels, increase pacemaker potentials, increase firing rate, increase HR
   - ventricles = increase contraction of heart
   - arterioles and veins = increase stretch
   ***end result changes to blood pressure feedback to the brain to increase to decrease

Question 5

what triggers a baroreceptor response?

Answer 5

changes in total peripheral resistance
- arteriole constricts
- increase R
- increases TPR
- increased MABP
- baroreceptors fire
- baroreceptor reflex
- decreased CO
= restored MABP

Question 6

how does the type of receptor affect the result of the sympathetic and parasympathetic neurotransmission form baroreceptor detection?

Answer 6

Question 7

how does autonomic control of arteriolar tone affect peripheral resistance?

Answer 7

• arteriolar tone is controlled by the release of norepinephrine
• the diameter of the blood vessel is controlled by the frequency of the signal from neurons
• increase norepinephrine release = more firing = more tone = vasoconstriction = increased peripheral resistance
• decrease norepinephrine = less firing = less tone = vasodilation = less peripheral resistance

Question 8

if you have low pressure form hemorrhage, how do baroreceptors react?

Answer 8