blood pressure Flashcards
define blood pressure
force exerted by the blood against the vessel wall per unit area (mmHg)
how is BP measured
sphygmomanometry
what are Korotkoff sounds created by
pulsatile blood flow through the compressed artery during BP measurement
when is blood flow silent during BP measurement
when the artery is no longer compressed
_____ stroke volume, _____ aortic compliance = increased pulse pressure
increased stroke volume
decreased aortic compliance (more stiff)
what is pulse pressure, and equation for it
measure of the strength of the pressure wave (difference between systolic and diastolic BP)
PP = SBP - DBP
SBP: systolic BP
DBP: diastolic BP
what is systolic BP and when is it measured
peak pressure
measured when heart contracts
what is diastolic BP and when is it measured
lowest pressure
measured when heart relaxes
what is mean arterial pressure, and 3 equations for it
(MAP) avg arterial BP over one cardiac cycle
MAP = DBP + (1/3)PP
or
MAP = (1/3)SBP + (2/3)DBP
or
MAP = HR x SV x TPR
2 places baroreceptors are located
aortic arch
carotid sinus
baroreceptor reflex mechanism for high BP
aortic arch & carotid sinus baroreceptors detect HIGH BP
->
send info to NTS
->
NTS tells CVLM to inhibit RVLM & excite vagal (CN 10) efferents
=
decrease in HR & BP
baroreceptor mechanism for low BP
aortic arch & carotid sinus baroreceptors detect LOW BP
->
decrease firing of CN 9 & 10 afferents
->
disinhibit RVLM & inhibit vagal tone
=
increase in HR & BP
where are pre-motor sympatheic neuron cell bodies located
RVLM
where are 2nd order afferents located
NTS
where are pre-ganglionic parasympathetic vagal efferents located
nucleus ambiguus
where are pre-ganglionic sympathetic nerves located
intermediolateral spinal column
where are the GABA-nergic nerves located (that then travel to RVLM)
CVLM
sympathetics cause _____ release, which binds to _____
norepi
beta1
parasympathetics cause _____ release, which binds to _____
Ach
M2
at what HR is SNS in control, and at what HR is PNS in control
SNS controls HR > 100
PNS controls HR < 100
at what speed does PNS change HR and how
rapidly
fast-acting K+ channels & rapid hydrolysis of Ach
at what speed does SNS change HR and how
slowly
slow reuptake of norepi from terminals & slow cAMP-mediated pathway
mechanism of how SNS changes resistance in vasculature
sympathetics = norepi = alpha1 receptor binding
->
increases TPR (total peripheral resistance)
->
decreases vessel/artery radius
->
increases resistance
arteries are _____ vessels, veins are _____ vessels
arteries = resistance
veins = compliance
why are arteries resistance vessels
they’re good at controlling vasoactive tone
equation for resistance (R) using radius (r)
R = 1 / (r^4)
equation for relationship of flow (Q) and resistance (R)
Q = 1 / R
3 determinants of vascular resistance, and which one has greatest effect on resistance
viscosity
length
radius (greatest effect)
what does a baroreflex curve show, what does a steeper slope mean
the inverse relationship between BP and HR
steeper slope = higher baroreflex sensitivity
define vasovagal syncope
an event triggers the vagus nerve to induce rapid bradycardia, causing sudden drop in BP
equation relating flow, resistance, radius
Q = 1 / R = r^4
draw renin-angiotensin-aldosterone system
