Pharmacology chapter

PHARMACOLOGY

CHOLINERGIC TRANSMISSION & CHOLINERGIC DRUGS

78 practice questions · 35 study notes

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Questions

QUESTION 1

Which muscarinic receptor subtype predominantly mediates vagal bradycardia in the heart?

QUESTION 2

Which coordinated bladder response is produced by acetylcholine to promote voiding?

QUESTION 3

In addition to inhibiting cholinesterase, neostigmine has a direct action on which receptors?

QUESTION 4

What is the primary mechanism by which anticholinesterases protect acetylcholine from hydrolysis?

QUESTION 5

In a vessel with disease-damaged endothelium, acetylcholine causes vasoconstriction. Which mechanism explains this response?

QUESTION 6

How does acetylcholine reduce impulse generation in the sinoatrial node?

QUESTION 7

Which muscarinic receptor subtype is primarily neuronal and participates in learning, memory and motor functions?

QUESTION 8

What mechanism causes ganglionic transmission blockade at high doses of anticholinesterases?

QUESTION 9

Which muscarinic receptor subtype mediates visceral smooth muscle contraction, glandular secretion and vasodilatation through EDRF release?

QUESTION 10

A higher dose of pilocarpine produces a rise in blood pressure and tachycardia. What mechanism is proposed for this response?

QUESTION 11

Which cardiovascular pattern is common with moderate doses of many anticholinesterases?

QUESTION 12

Which agent selectively stimulates nicotinic receptors at the skeletal muscle endplate?

QUESTION 13

Which nicotinic receptor subtype constitutes the primary pathway of transmission in autonomic ganglia?

QUESTION 14

What receptor architecture allows nicotinic receptors to produce rapid depolarization?

QUESTION 15

Why does intravenously injected acetylcholine produce no central effects?

QUESTION 16

A patient develops muscle twitching and fasciculations after an anticholinesterase. What process directly accounts for these findings?

QUESTION 17

Which choline ester is markedly potentiated by anticholinesterases?

QUESTION 18

Which change in aqueous outflow accompanies muscarinic contraction of the ciliary muscle and contributes to reduced intraocular tension?

QUESTION 19

Contraction of which ocular muscle produces miosis during muscarinic stimulation?

QUESTION 20

Which drug used for symptomatic relief in Alzheimer's disease inhibits cerebral acetylcholinesterase and also has weak nicotinic receptor agonist activity?

QUESTION 21

Where is acetylcholine synthesized locally in a cholinergic neuron?

QUESTION 22

After atropine administration, a high dose of acetylcholine produces tachycardia and a rise in blood pressure. What mechanism explains this response?

QUESTION 23

Which pair of secretions remains unaffected by the muscarinic actions of acetylcholine?

QUESTION 24

What is the effect of botulinum toxin on acetylcholine release from cholinergic nerve terminals?

QUESTION 25

Which autonomic ganglia are stimulated by the nicotinic action of acetylcholine?

QUESTION 26

Which step in acetylcholine synthesis is identified as rate limiting?

QUESTION 27

Which organophosphate has a quaternary structure, is water soluble, and was used as a long-acting miotic?

QUESTION 28

Which condition is a contraindication to anticholinesterase use, rather than a condition requiring cautious use?

QUESTION 29

Vesamicol blocks which process in a cholinergic nerve terminal?

QUESTION 30

Which cholinergic agonist is classified as an alkaloid?

QUESTION 31

What happens to choline after acetylcholine is hydrolyzed following its release?

QUESTION 32

What response underlies the modulatory role of subsidiary muscarinic receptors in autonomic ganglia?

QUESTION 33

Which enzyme is strategically located at cholinergic sites to inactivate acetylcholine instantaneously?

QUESTION 34

By which mechanism do anticholinesterases produce cholinomimetic actions?

QUESTION 35

Which endothelial mediator diffuses to smooth muscle and causes relaxation?

QUESTION 36

Which drug selectively stimulates muscarinic receptors?

QUESTION 37

What response is mediated by neuronal nicotinic receptors in the adrenal medulla?

QUESTION 38

Which pairing correctly describes the two classes of acetylcholine receptors?

QUESTION 39

Activation of prejunctional muscarinic autoreceptors on postganglionic cholinergic nerve endings produces which effect?

QUESTION 40

What chemical change produces aging of phosphorylated acetylcholinesterase?

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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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