Neural Control of Blood Flow Flashcards
where are the baroreceptors located?
carotid sinus & aortic arch
where is the carotid sinus located?
at the end of the carotid artery, as it splits into internal & external carotid arteries
what nerve carries nervous input to the carotid sinus?
CN IX
what nerve carries nervous output from the carotid sinus?
CN X
what nerve carries afferents to the aortic arch?
CN X
what nerve carries efferents from the aortic arch?
CN X
what increases the rate of firing of baroreceptors?
high BP
how do baroreceptors return high blood pressure to normal?
- 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
where are chemoreceptors located?
in the carotid bodies
chemoreceptors connect ____ to ____
breathing
heart rate
what do chemoreceptors respond to?
decreased O2 or increased CO2
what do chemoreceptors do?
increase breathing rate and turn on SNS
what changes occur to SNS activity, PSNS activity, plasma renin activity, and heart rate in response to standing up from a supine position?
- increased SNS
- decreased PSNS
- increased renin release
- increased HR
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?
all but renal blood flow would increase
(decreased BP at level of carotid sinus)
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?
all would increase
what changes to oxygen, carbon dioxide, and hydrogen would be expected to cause the greatest activation of the chemoreceptor reflex?
- decreased O2
- increased CO2
- increased H
what is orthostatic hypotension?
when changing from supine/sitting to standing, gravity causes blood to “drop” to feet which decreases blood to baroreceptors
what is the effect of orthostatic hypotension?
increase in SNS activity
what is the bainbridge reflex?
to prevent damming of blood in veins, must increase HR in response to increased BP
what is the effect of the bainbridge reflex?
increase BP leads to increased HR
(‘bridge’ between HR & hypertension)
what is the CNS ischemic response?
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
what is the effect of the CNS ischemic response?
mass sympathetic discharge to increase BP to brain leads to organ failure
what is the cushing reaction?
if CSF pressure > BP and causes collapse of blood vessels leading to a CNS ischemic response
what is the effect of cushing reaction?
mass sympathetic discharge to increase BP to brain leads to organ failure due to high CSF pressure (special type of CNS ischemic response)
what changes would occur to venous hydrostatic pressure in the legs, heart rate, and renal blood flow when standing up from a supine position?
- increase pressure
- increase HR
- decrease renal blood flow
