ANS sympatholytics Flashcards
Sympathetic NTs
-norepinephrine
-epinephrine
-adrenergic
veins and arteries only controlled by
SNS
Cardiac muscle receptors
-B1
Vasc smooth muscle receptors
-a1
CNS receptors
-a1 and a2
BP=
CO x TPR
CO=
SV x HR
SV determined by
-cardiac contractility
-venous return to heart (preload)
-resistance to left ventricle to eject blood into aorta (afterload)
selectivity of adrenergic receptor agonists
-
Baroreceptor reflex when BP decreases
-activates sympathetic fibers that feed back and innervate heart (B1)
-inc HR - reflex tachycardia
-a1 constricts bloodvessels
-inhibits vagus PSNS!
=inc blood pressure
Baroreceptor reflex when BP increases
-inhibits sympathetic
-activates vagus (PSNS)
-dec HR - reflex bradycardia
-no direct effect on blood vessels
=dec BP
Phenylephrine
-act a1
-inc systolic pressure
-vasoconstriction
-DEC HR
-activate baroreceptor to decrease HR
Epinephrine
-B and a receptors
-inc pressure and HR
-a1 vasoconstriction
-B2 vasodilation
-B1 positive inotropic and chronotropic effects
-ACTIVATE baroreceptor reflex that mitigates direct effects
Isoproterenol
-B receptors
-dec diastolic pressure, inc pulse pressure HR
-vasodilation
-positive I and C effects
-activate baroreceptors
if patient stands up really fast what is the baroreceptor response
-activated to inc CO, and vascular resistance to raise BP
Classes of anti-HTNs
-diuretics
-sympatholytics
-vasodilators
-renin-angiotensin antagonists
B-blocker action
-dec HR, contractility, renin secretion
a and b blockers
–dec HR, contractility, renin secretion
-smooth muscle relaxation
central a2 agonist action
-dec sympathetic tone
peripheral a1 antagonists
-vasc smooth muscle relaxation
a1 ANTAgonist drugs
-prazosin
-terazosin
-doxazosin
-double ring and piperazine ring
a1 Antagonist
-excreted in bile
-vasodilators
-relax smooth muscle and enlarge prostate
-NO reflex tachycardia
Prazosin vs phentolamine
-dec TPR via a1
-activate baroreceptor
-inc NE release
-phentolamine blocks a2 tho so no negative feedback = cardiac overstimulation = reflex tachycardia
Prazosin and terazosin action
-a1 ANTAgonist arterioles and venules
-dec TPR
-less tachycardia than nonselective a
-renin release )consider diuretic)
Prazosin and Terazosin use
-BPH
-HTN (not first line)
-Reynaud;s disease (mrs pairitz)
a1 antagonist problems
-minor
-first dose: orthostatic hypotension and syncope