Parasympathetic Activation / Cholinomimetic Agents Flashcards
4 CNs involved in parasympathetic NS
- CN III
- CN VII
- CN IX
- CN X
All preganglionic neurons use what NT and act on what receptor
ACh; act on nicotinic receptors
What is unique about parasympathetic preganglonics?
Ae very long and synapse in ganglia near target organs; this makes their actions more localized
Parasympathetic postganglionic neurons use what NT and what receptor
ACh–> on muscarinic receptors
What is the difference in nicotinic and muscarinic receptors in terms of how they produce their effects
Nicotinic–> open ligand gated Na/K channels
Muscarinic–> activate GPCRs and effect 2nd messenger systems
Other than autonomic ganglia, where else in the body are nicotinic receptors found?
- at the NMJ; part of somatic nervous system
2. adrenal medulla (sympathetic NS)
Other than CNs, where else are parasympathetic nerves found?
2nd and 3rd SACRAL spinal nerves (hence name craniosacral system)
parasympathetic action in GI
increased motility and tone–> increased digestion
parasympathetic action in bladder
relaxes sphincter, increases muscle tone of bladder wall
Parasym NS action in eye
- miosis
2. ciliary muscle contraction (accomodation)
Parasym NS action on lung
Contraction–> increased bronchial tone
Parasymp NS action on heart
decreased HR; some decrease in contractility
parasymp activity in lacrimal glands
stimulate tears
parasymp activity in salivary gland
watery secretion
parasymp effect on g.u.
erection (of penis or clitoris)
mnemonic for orhanophosphate poisoning/ cholinergic excess
DUMBELSS
Not specific for only parasympathetic action; nicotinic and muscarinic receptors are found elsewhere too
what does DUMBELSS stand for
- diarrhea
- urination
- miosis
- bronchospasm
- excitation of muscle/CNS (nicotinic @ NMJ)
- lacrimation
- salivation
- sweating
other than parasympathetic post ganglionic nerve targets, where else in body are muscarinic receptors found
Sweat glands
organophosphate mechanism of injury
inactivates acetylcholineesterase–> ACh excess–> excess cholinergic stimulation
What two drugs are given for cholinergic excess/ organophosphate toxicity
- Atropine–> (blocks muscarinic rceptors)
2. Pralidoxime–> (regenerates acetylcholinesterase
ptosis and diplopia that worsens throughout the day
Myasthenia gravis
what drug is used to test for myasthenia gravis
edrophonium (Tensilon test)
50% M.G. asociated with thymic ______
hyperplasia
20% M.G. associated with thymic _____
atrophy
15% M.G. associated with thymic ________
tumor (thymoma)
What causes a Myasthenia crisis (symptom)
Rapidly progressing weakness in respiratory muscles
4 treatments for myasthenia gravis
- immunotherapy (cyclosporine, immunotherapy)
- Plasmapheresis
- Indirect cholinergic agent
- thymectomy
3 anticholinesterases useful for tx of Alzheimer’s
- Donepezil
- Galantamine
- Rivastigmine
who gets poisoned by organophosphates
farmers
4 direct cholinomimetic agonists
- Bethanecol
- Carbachol
- Pilocarpine
- Methacholine
direct ACh agonist given for postoperative ileus, neurogenic ileus or urinary retention
Bethanecol
direct ACh agonist given for glaucoma
Carbachol
agonist that is an analoque of ACh
Carbachol
agonist that is potent stimulator of sweat, tears, and saliva; given for glaucoma (both open and closed)
Pilocarpine
*cry, drool, sweat on your PILOw”
direct agonist given as challenge test for asthma
Methacholine
*stimulates muscarinic receptor in lung to induce bronchspasm
5 indirect agents (anticholinesterases)
- Neostigmine
- Pyridostigmine
- Edrophomium
- Physostigmine
- Donepezil
indirect agent for short term tx of myasthenia gravis
Neostigmine
indirect agent that reverses non-depolarizing NMJ blockers
Neostigmine
indirect agent used for long term tx of myasthenia gravis
Pyridostigmine
which indirect agent can cross the BBB
Physostigmine
With all chlinomimetic agents, exacerbation of what three conditions can occur
- COPD
- Asthma
- Peptic Ulcer Disease
indirect agent used for atropine overdose
Physostigmine
- “Phyxes” atropin OD
