ANS Flashcards
a-1 agonist effects
increases vascular smooth muscle contraction (vasoconstriction), mydriasis increases intestinal and bladder sphincter muscle contraction, glucose metabolism
a-2 agonist effects
decreases sympathetic tone, inhibits glucose metabolism and insulin release, lipolysis
inhibits the release of NE
increases platelet aggregation, aqueous humor
b-1 agonist effects
increases HR, contractility, dromotropy, EF%
renin release
increases hunger r/t ghrelin release in stomach
b-2 agonist effects
vasodilation, bronchodilation
Increases: lipolysis, renin release
inhibits insulin release and stimulates gluconeogenesis and glucolysis
Decreases: uterine tone, relaxes ciliary muscle
DA-1 agonist effects
renal, cerebral, coronary and splanchnic arteries vasodilation
DA-2 agonist effects
modulates neurotransmitter release
Primary autonomic muscarinic receptor locations
M1 - postganglionic neurons of autonomic ganglia
M2- Heart, smooth muscle
M3 - glands, sweat, salvation, smooth muscle, endothelium
Primary autonomic nicotinic receptor locations
N1/Nm - skeletal muscles/NMJ
N2/Nn - postganglionic neurons
Two esterases that hydrolyze Ach?
Acetylcholinesterase
Plasma cholinesterase
Where are adrenergic receptors found presynaptically?
a-2 and DA-2
autoregulation that provides negative feedback
Where are adrenergic receptors found postsynaptically?
on target tissues/end organs
- cardiac muscle
- smooth muscle
- gland cells
- renal vasculature
3 naturally occurring catecholamines
norepi
epi
dopamine
catecholamine enzyme metabolism
COMT and MAO
Non-selective Catecholamines
Epi, Norepi, Dopa
Examples of direct agonists & receptor-selective Catecholamines
Phenylephrine (a-1)
clonidine (a-2)
dobutamine (b-1)
albuterol (b-2)
Indirect acting agonists
cocaine, amphetamine
Mixed Indirect/Direct agonist
ephedrine
a-1 agonists examples
phenylephrine
methoxamine
a-2 agonist examples
clonidine
alpha-methyl-dopa
dex
Mixed alpha/beta agonists examples
norepi
epi
b-1 selective agonist example
dobutamine
nonselective b-(1&2) agonist example
isoproterenol
b-2 selective agonists examples
albuterol, terbutaline, metaproterenol
a-1 selective antagonist examples
prazosin, terazosin, doxazosin, tamsulosin
non-selective alpha antagonists
inhibitory, sympatholytics
phentolamine (competitive)
phenoxybenzamine (non-competative/irreversible)
sympathomimetics are (agonists/antagonists)
agonists
sympatholytics are (agonists/antagonists)
antagonists
“blockers”
Mixed adrenergic (alpha/beta) antagonist
labetalol
Nonselective beta antagonists
propranolol, pindolol, timolol
B-1 selective antagonists
BEAM (cardiac selective) betaxolol esmolol atenolol metoprolol
Use ____ with caution in pts with asthma
B-2 blockers
Use ___ with caution in patients with cardiac insufficiency
beta-blockers - can decrease HR, contractility, and reduce CO
pheochromocytoma
adrenal gland tumor causes the release of catecholamines
use non-selective alpha-blockers
- phenoxybenzamine
- phentolamine
Norepi infusion rate
0.01-3 mcg/kg/min
1-20 mcg/min
Epi infusion rate
0.02-2 mcg/kg/min
1-20 mcg/min
Dopamine infusion rate
5-10 mcg/kg/min
Dobutamine infusion rate
.5-20 mcg/kg/min
Isoproterenol infusion rate
- 5-5 mcg/min
uses: heart blocks, transplants
phenylephrine dosing
bolus: 50-100 mcg pushes q1-2 min for hypotension
infusion: 10-200 mcg/min
esmolol dosing
bolus: 0.5-1mg/kg over 30 seconds
infusion: 50-300 mcg/kg/min
labetalol dosing
5-80 mg IV
a1 receptors: autonomic review
- postsynaptic
- Gq protein coupled, activates phospholipase C, PIP2 –> IP3 + Dag
a2 receptors: autonomic review
- presynaptic
- Gi protein coupled, inhibits Adenyl cyclase, ATP –> X –> cAMP
b1 & b2 receptors: autonomic review
- postsynaptic
- Gs protein coupled, activates adenyl cyclase, ATP –> cAMP
Factors that affect Blood pressure
CO (HR x SV)
Total peripheral resistance
Factors that affect HR + Contractility
increased by: SNS activity, B1 + Epi
decreased by: PSNS
Factors that affect stroke volume
contractility venous return (preload)
factors that affect venous return
blood volume is increased by: aldosterone, ADH, SNS
blood volume is decreased by: ANP
venous tone is increased by: SNS activity + Epi
factors that affect total peripheral resistance
circulating factors
innervation
viscosity of blood
local regulators
circulating factors that affect total peripheral resistance
increased by: ang-II, Epi, NE, ADH
innervation that affects total peripheral resistance
increased by: A1 receptors + NE
decreased by B2 receptors + Epi
local regulators that affect total peripheral resistance
increased by: endothelin, O2
decreased by: NO, H+, adenosine, PG, Bradykinin
