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62 Cards in this Set
- Front
- Back
The cholinergic system centers on which neurotransmitter?
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Acetylcholine
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How is Acetylcholine synthesized?
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1. choline transported from plamsa into nerve cell via Na carrier (like dopamine)
2. Choline and acetyl CoA combine with assistance of acetyltransferase to create Acetylcholine 3. Ach is transported to synaptic vesicles y proton antiporter for protection |
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Choline transport into the cell is inhibited by ____
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hemicholinium
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Describe the steps of Acetylcholine/ cholinergic transmission.
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1. Ach is synthesized in nerve cell and stored in vesicles
2. action potential arrives, triggering Ca influx and vesciles are dumped into synaptic cleft 3. Ach binds to postsynaptic receptor (can also bind back to presynaptic receptor) |
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_____ breaks down Ach (like MAO breaks down catecholamines)
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Acetylcholinesterase (AChE)
(also butylcholinesterase but less specific and not as effective) |
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What are the two types of cholinergic receptors?
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Nicotinic
Muscarinic |
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Describe the targets of the various muscarinic receptors.
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- M1= neural: CNS, PNS, gastric parietal cells
- M2= cardiac, bladder, lung - M3= Glandular, exocrine, smooth muscle, bladder, eye - M1,3,5 coupled to G-proteins responsible for stimulation of phospholipase C - M2,4 coupled to G-proteins for adenylcyclase inhibition and K+ channel activation |
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Describe the targets of nicotinic receptors.
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Nn or N2= autonomic ganglia
Nm or N1= NMJ - somatic motor end plates |
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Where does Ach bind?
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- preganglionic synapses of sympathetic and parasympathetic ganglia (Nm, M1, M2, M3)
- parasympathetic postganglionic neuroeffector junctions - all somatic motor end-plates on skeletal muscle. |
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Describe the responses mediated by the M3 muscarinic receptor.
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- dec. BP
- inc GI - empty bladder - empty rectum - stimulate glands - constrict bronchioles - accommodate for near vision - pupil constriction (miosis) |
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Describe the response mediated y a M2 Muscarinic receptor
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Dec heart rate
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Direct-acting cholinomimetics can be divided into what two groups?
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Choline Esters (acetylcholine, bethanecol)
Alkaloids (pilocarpine) |
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Indirect acting cholinomimetic drugs are called ___ and include what two subgroups?
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1. cholinesterase inhibitors
2. Carbamates (physostigmine, neostigmine, pyridostigmine, edrophonium) Phosphates (isoflurophate, antidote, pralidoxime) |
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Describe the pharmacological effects of the cholinergic system on the cardiovascular system.
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1. Vasodilation - all vascular beds including pulm and cardiac
2. negative chronotropy - direct and indirect (decreases rate itself, and inhibits adrenergic activation) 3) decreased rate of conduction in SA and AV nodes 4) decrease force of contraction (neg. inotropy) |
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Describe the pharmacological effects of the cholinergic system on the GI system/
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1. increse GI tone, contraction, peristalsis
2. increased secretory activity 3. increased motility (nausea, belching, vomiting, cramping, defecation) |
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Describe teh effects of acetylcholine on the urinary tract.
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1. increase ureteral peristalsis, detrusor contraction (bladder emptying), inc. maximal voiding pressure, dec. capacity of bladder
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Describe the cholinergic effects on:
a) glands b) respiratory system c) eyes |
a) stimulation of all glands that receive parasympathetic innervation (lacrimal, tracheobronchial, salivary, digestive, and exocrine glands)
b) inc. secretions, bronchoconstrictin c) miosis (constriction) |
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Describe the properties of bethanechol:
a) receptors b) sites c) action d) indication e) adverse reaction |
a) Muscarinic 1,2,3
b) smooth musculature of bladder, GI c) inc. GI motility and tone, empty bladder d) stimulate bladder in postpartum orpost op retention; postop abd distention and gastric atony and retention e) sweating, salivation, flushing, HOTN, nausea, diarrhea, abd pain, bronchospasm |
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___ can be used as an alternate to pilocarpine in Sjogren syndrome.
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Bethanechol
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Describe the properties of carbachol (carbamylcholine).
a) Receptors b) effect c) Indication d) adverse |
a) Muscarinic 1,2,3; weak nicotinic
b) CV and GI- first stimulate, then depress. May also cause epi release form medulla c) rare - miotic for glaucoma d) few when used in eye |
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Describe the properties of methacholine:
a) receptors b) action c) indication |
a) Muscarinic 1, 2, 3
b) bronchoconstriction (highly unpredictable cardiac effects) c) diagnostics for asthma/ allergy (pt given, if causes attack they have asthma, wont cause problem in healthy person) |
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Name 3 cholinomimetic alkaloids or analogs.
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Pilocarpine
Muscarine Arecoline |
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Describe the target of
a) muscarine b) pilocarpine c) arecoline |
a) muscarinic receptor sites
b) muscarinic action, but anomalous CV response and sweat glands are really sensitive to it c) nicotinic receptor sites |
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Describe the properties of pilocarpine:
a) receptors b) effect c) indication d) adverse rxn |
a) Muscarinic 1,2,3
b) miosis and contractionof ciliary muscle c) narrow and wide-angle glaucoma d) CNS effects, sweating, salivation |
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What ways should Ach be administered?
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oral or SQ for systemic, in eye for local
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What is the antidote to cholinergic agonists?
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Atropine, epi if severe
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What patients are contraindicated for choline ester use?
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- asthmatics
- hyperthyroidism - coronary insufficiency - peptic ulcer disease |
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Indirect cholinomimetic drugs are also known as ____ and may be ___ or ___
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1. cholinesterase inhibitors
2. reversible (water soluble) 3. irreversible |
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How do reversible cholinesterase inhibitors work?
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bind to AchE and block active site, preventing from binding to Ach.
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Give 5 examples of reversible cholinomimetic drugs.
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1. physostigmine
2. neostigmine 3. pyridostigmine 4. edrophonium 5. tacrine donzepil, rivastigmine, galantamine |
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Give examples of irreversible cholinomimetic drugs.
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- organophosphates
- echothiopate - tabun - sarin - soman - parathion - malathion |
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Physostigmine is used in what clinical settings? What is it's action?
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1. glaucoma, increased GI/Gu motility, reverse TCA effects, reverse CNS effects of atropine
2. amplifies effects of Ach |
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What drugs can be used to treat myasthenia gravis or reversal of neuromuscular block?
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Neostigmine
Pyridostigmine Edrophonium (amplifies Ach, improves strength) |
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____ are non-1st line durgs for glaucoma that are irreversible indirect amplifiers of Ach
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Isoflurophate, Echothiophate
(organophosphates) |
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Describe the effects of AchAse inhibition on:
a) general b) GI c) Eye d) Pulm e) CNS f) skeletal muscle g)CV |
a) amplify effects of Ach, muscarinic and nicotinic effects
b) diarrhea, urination, vomiting, salivation c) miosis d) bronchoconstriction, secretion e) tremor, anxiety, convulsion,c oma f) fasciculation g) hypotension |
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What is the DUMBELS mneumonic?
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- used to describe cholinergic effects:
D: diarrhea U: urination M: miosis B: bronchoconstriction E: excitation (CNS, muscle) L: lacrimation S: sweating/ salivation |
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Describe the mneumonic
M T W tH F |
- nicotinic presentations
M: mydriasis (dilated pupils), muscle twitching T: tachycardia W: weakness tH: hypertension, hyperglycemia F: fasciculations |
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Describe the MOA for muscarinic antagonists.
a) CNS b) eye c) bronchi d) GI e) GU f) CV g) Glands |
a) drowsiness, antiparkinson action, amnesia, delirium
b) dry eyes, mydriasis, reduced lacrimal secretion c) bronchodilation d) relaxation, slowed peristalsis e) urinary retention f) bradycardia then tachy g) decrease secretion |
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WHat describes the effects of antimuscarinic OD?
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"red as a beet, dry as a bone, blind as a bat, mad as a hatter, hot as hades"
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In addition to antimuscarinic drugs, what other classes can cause anticholinergic toxicity?
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- H1 antagonists (benadryl)
- TCA OD (amitryptyline) - Atypical antipsychotics (olanzapine) - Neuroleptic antipsychotics (chlorpromazine) |
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Where are nicotinic receptors found?
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- skeletal muscle
- smooth muscle (GI, blood vessels, bladder, bronchioles, uterus) - Cardiac - partially |
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What 2 drugs are used to treat organophosphate poisoning?
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1. atropine (antimuscarinic)
2. Pralodoxime (reactivates cholinesterase) |
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What is the only nicotinic agonist available to market?
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Nicotine (tobacco)
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What are the two categories of Nicotinic antagonists?
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1. ganglionic blocking agents
2. neuromuscular blocking agents |
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Name 2 ganglionic blockers. What are they used for?
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1. mecamylamine
2. trimethaphan block action of Ach on nicotinic receptors (but don't work on neuromuscular junctions, just ganglia) |
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Name the neuromuscular blockers.
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- atracurium
- cisatracurium - doxacurium - metocurine - mivacurium - pancuronium - rocuronium - tubocurarine - vecuronium |
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___ and ___ are competetive antagonists of Ach at ganglionic nicotinic receptors
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Trimethaphan, mecamylamine
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Describe the effects of ganglion-blocking (antinicotinic) drugs.
a) eye b) GI c) GU d) vessels e) glands |
a) mydriasis and cycloplegia
b) reduced motility and constipation c) urinary retention d) hypotension (vasodilation) e) dryness |
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___ are no longer used due to side effects but were initially used to treat HTN due to dissecting aneurysm
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Ganglionic blockers
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What are the two types of neuromuscular blockers?
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- Non-depolarizing
- Depolarizing |
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____ are competetive NM blockers that bind to ___ receptors to induce a blockade of Ach. An example is ____
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Non-depolarizing neuromuscular blockers,
Nicotinic cholinergic receptors d- Tubocurarine |
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____ are non-competetive NM blockers. How do they work? Example?
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1. Depolarizing
2. resistant to ach-ase so stay in synaptic cleft and prevent more action potentials from getting through - decamethonium |
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Name the NM agents that are:
a) long acting b) intermediate c) short |
a) curare
b) cistracurium, atracurium, pancuronium c) mivacurium, succinylcholine |
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NM Blockers that are metabolized by ___ have the longest DOA, ____ have teh shortest.
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1. longest = liver
2. shortest = plasma cholinesterases or carboxylesterase |
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Which medications elimination is not dependent on renal or hepatic function?
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cistacurium, atracurium (intermed)
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__ is not selective for the NMJ
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Curare (also works on ganglia??)
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Describe the MOA for neuromuscular blockers inducing tachycardia.
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1. nicotinic - block ganglia
2. muscarinin - anti vagoltic (gets rid of vagal stimulation) |
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_____ of neuromuscular blockers causes bronchospasm, hypotension, airway secretion.
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Histamine release
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NM blockers that have a short duration of action are likely metabolized how? Long?
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- short= plasma cholinesterases
- long = renal (liver shorter than renal but still long) |
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Describe the effect of botulinum?
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- inhibits release of Ach, interferes with nerve impulses and causes flaccid skeletal muscles
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Describe the characteristics of neuromuscular blocker toxicity.
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- respiratory paralysis (duh)
- malignant hyperthermia in succinylcholine (with genetic predisposition) |
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What medication is given to reverse malignant hyperthermia early in succinylcholine administration?
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Dantrolene
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