Neural Control of Blood Flow

Question 1

where are the baroreceptors located?

Answer 1

carotid sinus & aortic arch

Question 2

where is the carotid sinus located?

Answer 2

at the end of the carotid artery, as it splits into internal & external carotid arteries

Question 3

what nerve carries nervous input to the carotid sinus?

Answer 3

CN IX

Question 4

what nerve carries nervous output from the carotid sinus?

Answer 4

CN X

Question 5

what nerve carries afferents to the aortic arch?

Answer 5

CN X

Question 6

what nerve carries efferents from the aortic arch?

Answer 6

CN X

Question 7

what increases the rate of firing of baroreceptors?

Answer 7

high BP

Question 8

how do baroreceptors return high blood pressure to normal?

Answer 8

• increased firing rate turns off vasomotor center (vasoconstrictor area)
• decreases SNS activity
• increases CN X to heart -> decrease HR & force of contraction -> decreases Q
• decreases BP to normal

Question 9

where are chemoreceptors located?

Answer 9

in the carotid bodies

Question 10

chemoreceptors connect ____ to ____

Answer 10

breathing
heart rate

Question 11

what do chemoreceptors respond to?

Answer 11

decreased O2 or increased CO2

Question 12

what do chemoreceptors do?

Answer 12

increase breathing rate and turn on SNS

Question 13

what changes occur to SNS activity, PSNS activity, plasma renin activity, and heart rate in response to standing up from a supine position?

Answer 13

• increased SNS
• decreased PSNS
• increased renin release
• increased HR

Question 14

what changes would occur to HR, SNS activity, renal blood flow, and total peripheral resistance, when the carotid artery is isolated proximal to the carotid bifurcation and partially constricted with a tie around the vessel?

Answer 14

all but renal blood flow would increase
(decreased BP at level of carotid sinus)

Question 15

When moving from sitting to standing, what changes occur to mean circulatory filling pressure, strength of cardiac contraction, and SNS activity in response to activation of the baroreceptors?

Answer 15

all would increase

Question 16

what changes to oxygen, carbon dioxide, and hydrogen would be expected to cause the greatest activation of the chemoreceptor reflex?

Answer 16

• decreased O2
• increased CO2
• increased H

Question 17

what is orthostatic hypotension?

Answer 17

when changing from supine/sitting to standing, gravity causes blood to “drop” to feet which decreases blood to baroreceptors

Question 18

what is the effect of orthostatic hypotension?

Answer 18

increase in SNS activity

Question 19

what is the bainbridge reflex?

Answer 19

to prevent damming of blood in veins, must increase HR in response to increased BP

Question 20

what is the effect of the bainbridge reflex?

Answer 20

increase BP leads to increased HR
(‘bridge’ between HR & hypertension)

Question 21

what is the CNS ischemic response?

Answer 21

when BP <60 or there is lack of O2 or blood to brain, there is a last ditch effort to get more blood to the brain

Question 22

what is the effect of the CNS ischemic response?

Answer 22

mass sympathetic discharge to increase BP to brain leads to organ failure

Question 23

what is the cushing reaction?

Answer 23

if CSF pressure > BP and causes collapse of blood vessels leading to a CNS ischemic response

Question 24

what is the effect of cushing reaction?

Answer 24

mass sympathetic discharge to increase BP to brain leads to organ failure due to high CSF pressure (special type of CNS ischemic response)

Question 25

what changes would occur to venous hydrostatic pressure in the legs, heart rate, and renal blood flow when standing up from a supine position?

Answer 25

• increase pressure
• increase HR
• decrease renal blood flow