15 Central Neural Control of the Cardiovascular System

Question 1

What local influences affect the heart?

Answer 1

intrinsic beating (SAN)
Starling's Law

Question 2

What local influences affect the arterioles?

Answer 2

endothelial
myogenic
metabolic

Question 3

What local influecnes affect the capillaries?

Answer 3

diffusion

filtration

Question 4

What is the NA?

Answer 4

Nucleus Ambiguus

cell bodies of Vagal supply to the heart

Question 5

What is the RVLM?

Answer 5

rostral ventral lateral medulla

main site of neurones supplying the descending, sympathetic pathway

Question 6

How would a spinal transection affect blood pressure?

Answer 6

no sympathetic control of blood vessels

low ABP

Question 7

What are the sympathetic reflex influences on hormones?

Answer 7

Catecholamines
Vasopressin (ADH)
Renin-Angiotensin

Question 8

What are the 2 main regions for baroreceptors?

Answer 8

Carotid sinus

Aortic Arch

Question 9

What are the carotid sinus baroreceptors supplied by?

Answer 9

glossopharyngeal nerve

Question 10

What are the aortic baroreceptors supplied by?

Answer 10

vagus nerve

Question 11

What type of receptors are baroreceptors?

Answer 11

stretch receptors

Question 12

Where do baroreceptor afferents lead to?

Answer 12

Nucleus Tractus Solitarius (NTS)

Question 13

What is the significance of the threshold to baroreceptor activity?

Answer 13

about 60mmHg

there is baroreceptor activity at resting ABP

Question 14

When would the baroreceptor response be highest?

Answer 14

at the peak of systole

Question 15

What are the ultimate aims of the baroreceptor reflex?

Answer 15

to keep ABP lower than it normally would be

Question 16

What does the sympathetic nervous system do to increase CO?

Answer 16

increases HR
increases Contractility
Increases vasoconstriction

Question 17

What does the SNS do to increase TPR?

Answer 17

arterial vasoconstriction

Question 18

How does arterial vasoconstriction increase CO?

Answer 18

decreases capillary hydrostatic pressure

increases EDV
increases SV

Question 19

How does venoconstriction increase CO?

Answer 19

increases EDV

increases SV

Question 20

How does the PNS increase CO?

Answer 20

it reduces its’ action, facilitating the increase of HR by the SNS

Question 21

What do the glossopharyngeal and the vagus nerve do to the NTS in the baroreceptor reflex?

Answer 21

stimulate it

Question 22

What effect does the NTS have on the NA?

Answer 22

the NTS stimulates the NA

this increases vagal stimulation to the heart

Question 23

What effect does the NTS have on the RVLM?

Answer 23

it inhibits it (as this facilitates sympathetic drive of the heart)

Question 24

What effect does the NTS have on the CVLM?

Answer 24

it stimulates it

the CVLM provides inhibitory input to the RVLM

Question 25

What is the role of the preoptic hypothalamic nucleus in the baroreceptor reflex?

Answer 25

it is quite a long, inhibitory pathway to the RVLM from the NTS may have a role in telling integrating areas of hypothalamus about the change in ABP

Question 26

What is the role of the PVN and SON?

Answer 26

these are inhibited in the reflex, reducing the release of ADH

Question 27

Where is most of the constriction as a response to a fall in ABP? how does this increase ABP?

Answer 27

GI (25%) Skeletal muscle (20%) also in the skin providing we are not thermoregulating increases TPR

Question 28

What proportion of our TPR is supplied by the kidneys?

Answer 28

20%

Question 29

What is the brain's autoregulatory range?

Answer 29

60-160

Question 30

What is the effect of cutting the sinus an aortic nerves on ABP on a dog? Why is this interesting?

Answer 30

ABP becomes far more variable, but still sticks around the mean this would suggest there is something keeping it in check somewhat... this is the volume receptor reflex

Question 31

Where are the stretch receptors of the volume receptor reflex? what supplies them?

Answer 31

right atrium | supplied by Vagus nerve

Question 32

What happens to the CNS if there is an increase in blood volume in the volume receptor reflex?

Answer 32

decreased activity to the NTS and PVN

Question 33

What happens to the kidney if there is an decrease in blood volume in the volume receptor reflex?

Answer 33

increased sympathetic activity: increases renal vasoconstriction, reducing GFR increases renin release increase ADH action

Question 34

When is the volume receptor reflex used?

Answer 34

decreased distension (when standing, haemmorrhage, dehydration) increased distension (when supine, large fluid intake)

Question 35

What is the difference in response time between the baroreceptor and the volume receptor reflex?

Answer 35

baroreceptor reflex is much faster than volume receptor reflex

Question 36

When might the set point of the baroreceptor reflex change?

Answer 36

acutely - exercise or mental stress chronically - hypertension, renal failure