Question | Answer |
SNS | thoraco-lumbar
pre-ganglonic: short axon into prevertebral chain
post-ganlionic: long axon to organs
widely spread system
one neuron can go to MULTIPLE places |
Exception to SNS ganglia | adrenal glands
long pre and short post
neuron that goes here ONLY goes here |
PSNS | brain stem and sacral cord
long pre and short post
very restrictive; one neuron to one place |
Acetylcholine (Ach) | used by PRE-ganglionic axons
agonist for NICOTINIC receptor |
Norepinephrine (NE) | major transmitter for SNS
activates alpha 1/2 > beta 1 (mixed adrenergic agonist)
used for hypotension |
Exception to NE for SNS | adrenal gland; chromaffin cell is post ganglia and releases Ach whcih which stimulates Epinephrine |
Flow of transmitter signaling SNS | Ach --> nicotinic --> NE --> Alpha/beta |
PSNS and somatic | cholinergic system |
Flow of transmitter signaling for heart (PSNS) | Ach --> nicotinic --> Ach --> muscarinic |
Flow of transmitter signaling for somatic | Ach --> nicotinic --> Ach --> nicotinic |
In the SNS terminal, what is dopamine converted to? | NE |
What causes the "lipid bubble" containing NE to move to the surface and open into the synapse? | Ca++ |
Uptake 1 | NE transporter; pulls NE out of the synapse and back into terminal where MAO breaks it down |
receptors that exist in tissues but DO NOT have direct innervation | Extra junctional |
this receptor is activated to slow the system down because of too much NE; type of feedback inhibition | pre-synaptic alpha 2 |
Enzymes that degrade trasnmitters | COMT |
Predominant tone belongs to which system? | PSNS; exception is blood vessels |
Low concentrations of NE will have high affinity for what? | Alpha |
Epinephrine | beta 1/2 >> alpha 1/2 (mixed adrenergic agonist)
used for: asthma, anaphylactic shock, cardiogenic shock, and prolongs actions of local anesthetics |
Low concentrations of Epi have high affinity for what? | beta 1/2
BUT, if dose increases 10x then alpha (dilate) will out-power beta (constrict) |
Dopamine | alpha 1 and beta 1 (mixed adrenergic agonist)
CNS functions
was once used to treat CHF
indirectly acting adrenergic agonist |
pseudoephedrine | alpha and beta (mixed adrenergic agonist)
used for colds |
Phenylephrine | selective alpha 1 agonist
used for hypotension, bradycardia, and as decongestant |
Methoxamine | selective alpha 1 agonists |
Clondine | selective alpha 2 agonist
centrally acting anti hypertensive |
A patient with high SNS activity will have? | HYPERtension |
Isoproternol | beta 1/2
non selective beta agonist
cardiac transplants |
Dobutamine | Selective beta 1 agonist
low doses will increase force of contraction but NOT heart rate |
metaproterenol | selective beta 2 agonist
treats asthma |
albuterol | selective beta 2 agonist
asthma: 1/2 life 6-7 hrs |
salmetrol | selective beta 2 agonist
asthma: 1/2 life 12 hrs |
Phentolamine | non-selective alpha 1/2 antagonist
used for OD of alpha agonists; used in pts with pheochromocytoma
Side effects: orthostatic hypotension, tachycardia, PSNS effects |
Prazosin and silodosin | selective alpha 1 anatagonists |
terazosin | selective alpha 1 antagonist
anti hypertensive agent
water soluble |
Propanolol, Nadolol, Timolol and Pinolol | Non-selective beta antagonists
Tx: HTN, angina, MI, arrhythmia, stage fright, glaucoma, tremor, migraine, and anxiety
contraindication: asthma attack in those with asthma |
Labetalol and carvedilol | non selective beta antagonists
also work on alpha 1 |
Tyramine | dietary substance
indirectly acting adrenergic agonost |
ephedrine | indirectly acting adrenergic agonist
can also bind to beta receptors
increase SNS activity |
amphetamine | indirectly acting adrenergic agonist |
Indirectly acting agonists | DO NOT bind to receptors but produce effects that look like SNS agonists
cause increase in NE release; more rapid |
Uptake blockers | cocaine
tricyclic antidepressants
amphetamine (high doses) |
MAO inhibitors | pargyline and tranylcypromine |
What could cause increase in BP in those taking MAO inhibitors? | Tyramine |
Cholinergic receptors are? | nicotinic and muscarinic |
what has no clinical use? | Ach as muscarinic agonist |
Bethanechol | choline esther; M agonist
effects mostly on GI and urinary systems when administered orally or subQ
prevents urinary retention
side effects: over-stimulation of M receptors |
carbachol | choline esther; M and N agonist
produce miosis(constrict) druing ocular surgery |
Pilocarpine | alkaloid; M agonist
NO N effects
used topically to treat glaucoma
somewhat selective for salivary glands
used for Sjorgen's syndrome
Side effects: over-stimulation of M receptors |
Atropine and Scopolamine | Belladonna alkaloids; M anatagonists (selective)
used when PSNS tone is desirable
pre-op use for reduction of salivation/bronchial secretions
treat poisoning by AchE inhibitor |
Atropine toxic actions | dry as a bone, hot as a pistol, red as a beet, blind as a bat, and mad as a hatter |
Cholinesterase (AchE inhibiotrs) | agents used to enhance transmission at cholinergic junctions |
carbamates | bind to the esteratic site of AchE (reversible) |
Physostigmine | carbamate
readily penetrates CNS
drug of choice to treat poisoning with atropinic agents |
Neostigmine | carbamate
does NOT penetrate CNS
used to treat myasthenia gravis
used as antidote for overdose of "curare-like" drugs |
edrophonium | carbamate
short acting
diagnostic agent used to test for myasthenia gravis |
Donepezil (aricept) | carbamate
short term fix for alzheimer's |
Organophosphates | irreversibly phosphorylate serine hydroxyl at active site of AchE
ex: insecticides and nerve gases |
what is the only way to restore function after exposure to organophosphates? | make new enzymes; could take 2-3 weeks
antidote for insecticide= 2-pralidoxine (2-PAM) |
Botulinum toxin (Botox) | prevents Ach release from cholinergic neurons
AP occurs, but nothing happens and muscle is paralyzed |
What is used in surgery to promote skeletal muscle relaxation? | Neuromuscular (NMJ) blocking agents |
Tubocurarine | NMJ blocker
long duration |
Pancuronium | NMJ blocker
intermediate duration |
Succinylcholine | NMJ blocker
used for setting bones |
How are NMJ blockers reversed? | With AchE |
terbutaline | beta 2 agonist
used for premature labor to relax uterus |