Pharmacology chapter
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PHARMACOLOGY

CHOLINERGIC TRANSMISSION & CHOLINERGIC DRUGS

78 practice questions · 35 study notes
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Questions

QUESTION 41
Why is the action of edrophonium brief?
QUESTION 42
Which statement describes the use of atropine in hallucinogenic mushroom poisoning caused by muscimol and related compounds?
QUESTION 43
A patient develops characteristic muscarinic symptoms within an hour of eating Inocybe mushrooms. Which drug promptly reverses these symptoms?
QUESTION 44
Why does intravenous acetylcholine generally produce no effect on skeletal muscle?
QUESTION 45
Compared with lipid-soluble anticholinesterases, which action is more prominent with neostigmine and other lipid-insoluble quaternary ammonium agents?
QUESTION 46
A patient develops gastrointestinal, hepatic and renal injury many hours after eating Amanita phalloides. What is the stated mechanism of the responsible peptide toxins?
QUESTION 47
Which receptor action characterizes muscarine?
QUESTION 48
Which structural feature accounts for the lipid solubility of physostigmine?
QUESTION 49
Which amino acid residues form the esteratic site of acetylcholinesterase?
QUESTION 50
Why can excessive anticholinesterase dosing cause weakness in a patient with myasthenia gravis?
QUESTION 51
Which receptors are targeted by antibodies in myasthenia gravis?
QUESTION 52
Which drug is identified as the preferred miotic for glaucoma?
QUESTION 53
How are miotics used to prevent or break adhesions between the iris and lens or between the iris and cornea?
QUESTION 54
Which pharmacokinetic feature distinguishes physostigmine from neostigmine and its congeners?
QUESTION 55
A patient receiving an anticholinesterase for myasthenia gravis develops intolerable muscarinic adverse effects. Which drug can be added to block these effects?
QUESTION 56
The ciliary muscle whose tone is increased by miotics in glaucoma is attached to which structure?
QUESTION 57
Which anticholinesterase has a duration of action of 10–30 minutes and is suitable only as a diagnostic agent for myasthenia gravis?
QUESTION 58
Which adverse effect caused tacrine to fall into disuse despite symptomatic improvement in Alzheimer's disease?
QUESTION 59
By which principal action do corticosteroids improve myasthenia gravis?
QUESTION 60
A patient using pilocarpine eye drops reports diminished vision, particularly in dim light. Which mechanism explains this adverse effect?
QUESTION 61
A patient with myasthenia gravis develops acute respiratory muscle weakness constituting a myasthenic crisis. Which respiratory intervention is described for management?
QUESTION 62
How does persistent depolarization of muscle endplates affect neuromuscular transmission?
QUESTION 63
Which pattern of muscle weakness characterizes myasthenia gravis?
QUESTION 64
What central nervous system response is produced by brain-penetrating lipophilic anticholinesterases before the toxic effects associated with higher doses?
QUESTION 65
Which group represents the skeletal muscle manifestations of anticholinesterase poisoning?
QUESTION 66
Which manifestations occur immediately at the site of exposure in anticholinesterase poisoning?
QUESTION 67
A patient has carbaryl poisoning. Why is pralidoxime contraindicated according to the described mechanism?
QUESTION 68
What is the initial intravenous test dose of edrophonium in the ameliorative test for myasthenia gravis?
QUESTION 69
Why does pralidoxime fail to reactivate cholinesterase in the central nervous system?
QUESTION 70
What is the usual cause of death in anticholinesterase poisoning?
QUESTION 71
Why may atropine be administered before neostigmine during pharmacological testing for myasthenia gravis?
QUESTION 72
What condition must be excluded before using neostigmine for postoperative paralytic ileus or urinary retention?
QUESTION 73
Which manifestation of anticholinesterase poisoning is not reversed by atropine?
QUESTION 74
A patient with anticholinesterase poisoning develops convulsions. Which drug is specified for their judicious control?
QUESTION 75
Which drug is listed among the relatively cerebroselective anticholinesterases commonly used for Alzheimer's disease?
QUESTION 76
Which drug remains the primary antidote in organophosphate poisoning, with oximes serving an adjunctive role?
QUESTION 77
A patient has residual muscle paralysis after receiving a competitive neuromuscular blocker during surgery. Which drug is described as rapidly reversing this paralysis?
QUESTION 78
Why should pralidoxime treatment in organophosphate poisoning begin within the first few hours?
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Study notes

Sites of acetylcholine neurotransmission
Acetylcholine is introduced as a major neurohumoral transmitter. →
Local synthesis of acetylcholine
The passage introduces the site of acetylcholine synthesis in cholinergic neurons. →
Acetylcholine synthesis, vesicular storage, release, and toxin effects
Cholinergic nerve terminals take up choline, synthesize and store acetylcholine, and release it in vesicular quanta. Specific inhibitors and toxins interrupt different steps. →
Cholinesterases and termination of acetylcholine action
Cholinesterases hydrolyze released acetylcholine. The source distinguishes acetylcholinesterase from butyrylcholinesterase by their location and function. →
Cholinoceptor classes and endothelial relaxation
Acetylcholine acts through muscarinic and nicotinic receptors, which have different signaling structures. The passage also describes an endothelial mediator of smooth muscle relaxation. →
Muscarinic receptor actions and distribution
Muscarinic receptors occur on autonomic effector cells and nerve endings, where they mediate effector responses and modulate transmitter release. →
Muscarinic receptor subtypes and their principal functions
Muscarinic receptors mediate neuronal, cardiac, smooth muscle, glandular and endothelial responses. A tissue may express several subtypes while one predominates. →
Cardiac M2 signalling and nicotinic receptor subtypes
This passage completes cardiac muscarinic signalling and describes the structure, locations and selective pharmacology of nicotinic receptors. →
Functions of neuronal nicotinic receptors
The neuronal nicotinic receptor entry describes responses in autonomic ganglia, the adrenal medulla and the central nervous system. →
Mechanisms of cholinergic drugs
Cholinergic drugs, also called cholinomimetics or parasympathomimetics, produce actions similar to acetylcholine. →
Cholinergic alkaloids and classification of acetylcholine actions
The passage lists alkaloid cholinergic agonists and introduces the receptor-based classification of acetylcholine actions. →
Muscarinic actions of acetylcholine on the heart, vessels and smooth muscle
Acetylcholine slows cardiac activity, generally dilates vessels through the endothelium, and contracts smooth muscle in several organs. →
Muscarinic effects on glands and the eye
Acetylcholine produces glandular secretion and ocular muscle contraction through its muscarinic actions. →
Nicotinic actions of acetylcholine on autonomic ganglia
Acetylcholine stimulates autonomic ganglia, with this effect becoming evident at higher doses. →
Acetylcholine actions on skeletal muscle
The skeletal muscle response to acetylcholine depends on how it reaches the muscle endplate. →
Choline esters: central effects, interactions and selected uses
Acetylcholine has route-dependent central effects. The passage also describes interactions of choline esters, bethanechol use and the actions of pilocarpine. →
Additional pilocarpine uses and muscarine
This passage continues the discussion of pilocarpine as an ocular miotic and introduces muscarine as a mushroom toxin. →
Types of mushroom poisoning and actions of arecoline
Mushroom poisoning differs by toxic principle, timing, predominant manifestations and treatment. →
Anticholinesterases: mechanism and chemical groups
Anticholinesterases enhance acetylcholine action by protecting it from enzymatic hydrolysis. →
Anticholinesterases: lipid solubility and enzyme interactions
Carbamates and organophosphates inhibit acetylcholinesterase through enzyme interactions whose stability determines the duration of inhibition. →
Enzyme aging and pharmacological actions of anticholinesterases
The passage explains persistent organophosphate inhibition and contrasts the effects of lipid-soluble and lipid-insoluble anticholinesterases. →
Anticholinesterase effects on ganglia, circulation and skeletal muscle
Anticholinesterases prolong acetylcholine action, but their effects differ by site and dose because muscarinic, ganglionic and neuromuscular responses interact. →
Anticholinesterases: endplate and central nervous system effects
The interpretable text describes neuromuscular blockade from persistent endplate depolarization and the central effects of brain-penetrating anticholinesterases. →
Anticholinesterases: peripheral effects, pharmacokinetics and individual agents
Anticholinesterases stimulate smooth muscles and glands, while individual drugs differ in absorption, tissue penetration, duration and clinical use. →
Selected anticholinesterases and precautions for their use
The passage describes agents used for Alzheimer's disease, organophosphate miotics, and conditions that restrict anticholinesterase use. →
Miotics in glaucoma: muscle actions
This short passage describes the initial muscle actions underlying the use of miotics in glaucoma. →
Ocular uses and adverse effects of miotics
The readable prose continues the explanation of miotics in glaucoma and describes their adverse effects and other ocular uses. The disrupted comparative table is not used. →
Myasthenia gravis: pathogenesis, symptoms and initial treatment
Myasthenia gravis is an autoimmune disorder affecting muscle-endplate nicotinic receptors. Anticholinesterases improve muscle strength without correcting the underlying disorder. →
Myasthenia gravis: immunotherapy, crisis and anticholinesterase overdose
This passage covers treatment of advanced myasthenia gravis and contrasts respiratory crisis with weakness caused by excessive anticholinesterase treatment. →
Edrophonium ameliorative test for myasthenia gravis
The target passage describes the initial administration sequence for an edrophonium diagnostic test. →
Diagnostic and therapeutic uses of anticholinesterases
This passage continues myasthenia gravis testing and describes several clinical uses and limitations of neostigmine and physostigmine. →
Cerebroselective anticholinesterases and onset of poisoning
The passage concludes the discussion of Alzheimer's disease therapy and introduces the exposure pattern and early manifestations of anticholinesterase poisoning. →
Clinical manifestations of anticholinesterase poisoning
Anticholinesterase poisoning produces secretory, ocular, respiratory, cardiovascular, muscular and central manifestations. →
Treatment of anticholinesterase poisoning: supportive care, atropine and oximes
Treatment combines termination of exposure, respiratory and circulatory support, control of convulsions and appropriate antidotes. →
Oxime therapy and chronic organophosphate neurotoxicity
The passage continues pralidoxime treatment, explains the limits of oxime therapy and describes delayed neurological effects of repeated organophosphate exposure. →
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