peripheral resistance control of Bp L12 Flashcards
unit of cardiac output
Q
equation of cardiac output
Q= change in pressure/ resistance
Blood pressure cal=
cardiac output x resistance
blood flow is determined by
diameter of a vessel
resistance means
the impediment to blood flow along a vessel
what is short term control of blood pressure
neurological -ANS
where are sympathetic fibres to
all vessels in the body except capillaries
what do sympathetic fibres release
noradrenaline
what receptors does noradrenaline interact with
alpha receptors
what does alpha receptor stimulation cause
vasocontriction= increased peripheral resistance
what does venous constriction cause
increased venous return which increases cardiac output
what cardiac effects does the sympathetic nervous system have
increase HR
inotropic effect (pump stronger)
lusitropic effect
at rest what is there an underlying stimulation of
sympathetic NS
what receptors detect pressure
baroreceptors
where are baroreceptors
arch of aorta
carotid sinuses
where are the carotid sinuses
in internal carotid arterties
what do baroreceptors detect
stretch
what do baroreceptors effect
they cause increased/ decreased sympathetic outflow
chemically a decreased Bp causes
a decreased PaO2
what detects decreased PaO2
chemoreceptors
what is long term Bp control
hormonal
2 renal controls of Bp
pressure diuresis
renin angiotensin system (RAAS)
what is pressure diuresis
increased Bp–> increased blood flow to kidneys–> increased urination—> decreased BP
what does a increased salt and water intake mean
higher Bp
what hormone is released after a fall in Bp
renin
what does renin do
converts angiotensinogen to angiotensin 1
what does ACE (angiotensin converting enzyme do)
converts angiotensin 1 to angiotensin 2
what does angiotensin 2 do
works on AT1 and AT2 receptors
what do AT1 and AT2 receptors do
vasocontriction
vascular hypertrophy
aldosterone release
what does aldosterone do
induces salt and water retention
what other hormones respond to pressure
natriuretic peptides arginine vasopressin (ADH)
what does natriuretic peptide do
respond to stretch—> salt loss and vasodilation
what does arginine vasopressin do
vasoconstriction
water retention
ending of ACE inhibitors
-pril
ending of angiotensin receptor blockers
-Sartan
what do steroids do
interfere with action of aldosterone
what can alpha blockers do
block alpha receptors so noradrenaline can’t bind decreasing peripheral resistance and Bp
what do beta blockers do
block beta receptors so noradrenaline can’t bind (SNS) decreasing peripheral resistance and heart rate
what do calcium antagonists end in
-ipine
what do calcium antagonists do
cause vasodilation by inhibiting Ca2+ from entering smooth muscle cells
