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Questions and Answers
What is the mechanism of action of indirect acting parasympathomimetics?
What is the mechanism of action of indirect acting parasympathomimetics?
- Activation of cholinergic receptors directly
- Stimulation of adrenergic receptors
- Blockade of cholinergic receptors
- Inhibition of cholinesterase enzyme (correct)
Which of the following is a reversible cholinesterase inhibitor mentioned in the text?
Which of the following is a reversible cholinesterase inhibitor mentioned in the text?
- Physostigmine (correct)
- Muscarine
- Pilocarpine
- Neostigmine
What effect does ACh have on the heart?
What effect does ACh have on the heart?
- Increase effective refractory period at the atrium (correct)
- Increase conduction at the A-V node
- Decrease atrial strength of contraction
- Increase heart rate
What effect does ACh have on smooth muscles in blood vessels?
What effect does ACh have on smooth muscles in blood vessels?
Which compound is mentioned as an irreversible cholinesterase inhibitor in the text?
Which compound is mentioned as an irreversible cholinesterase inhibitor in the text?
What is the main pharmacological action of ACh on smooth muscles in blood vessels?
What is the main pharmacological action of ACh on smooth muscles in blood vessels?
What is the main reason oximes must be given very early after exposure?
What is the main reason oximes must be given very early after exposure?
Which oxime is mentioned as more potent than pralidoxime?
Which oxime is mentioned as more potent than pralidoxime?
Which of the following is NOT a natural occurring alkaloid mentioned in the text?
Which of the following is NOT a natural occurring alkaloid mentioned in the text?
Which class of drugs is known for blocking muscarinic receptors without affecting nicotinic receptors?
Which class of drugs is known for blocking muscarinic receptors without affecting nicotinic receptors?
Which drug is mentioned specifically for eye applications in the text?
Which drug is mentioned specifically for eye applications in the text?
Which drug class has little central nervous system effects and is used in bronchial asthma?
Which drug class has little central nervous system effects and is used in bronchial asthma?
Which type of receptors in the parasympathetic nervous system are blocked by atropine?
Which type of receptors in the parasympathetic nervous system are blocked by atropine?
Which type of cholinergic receptor is found in the autonomic ganglia and is blocked by d-tubocurarine?
Which type of cholinergic receptor is found in the autonomic ganglia and is blocked by d-tubocurarine?
Which type of cholinergic receptor causes inhibition of adenyl cyclase leading to a decrease in cAMP?
Which type of cholinergic receptor causes inhibition of adenyl cyclase leading to a decrease in cAMP?
Which classification of parasympathomimetics includes drugs that act by directly binding to the receptors?
Which classification of parasympathomimetics includes drugs that act by directly binding to the receptors?
Which cholinergic agonist is a Choline ester?
Which cholinergic agonist is a Choline ester?
Which type of cholinergic receptor is G-protein coupled and causes stimulation of phospholipase C?
Which type of cholinergic receptor is G-protein coupled and causes stimulation of phospholipase C?
Flashcards
Parasympathomimetics
Parasympathomimetics
Drugs that mimic the effects of acetylcholine (ACh) on cholinergic receptors in the parasympathetic nervous system.
Cholinergic Receptors
Cholinergic Receptors
Two main types of receptors that bind acetylcholine: muscarinic and nicotinic.
Muscarinic Receptor
Muscarinic Receptor
A type of cholinergic receptor that is blocked by atropine, involved in various bodily functions.
Nicotinic Receptor
Nicotinic Receptor
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M1, M3, and M5 Receptors
M1, M3, and M5 Receptors
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M2 and M4 Receptors
M2 and M4 Receptors
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Nicotinic Receptor Mechanism
Nicotinic Receptor Mechanism
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Direct-acting Parasympathomimetics
Direct-acting Parasympathomimetics
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Indirect-acting Parasympathomimetics
Indirect-acting Parasympathomimetics
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Choline Esters
Choline Esters
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Acetylcholine's Effect on the Heart
Acetylcholine's Effect on the Heart
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Acetylcholine's Effect on Smooth Muscles
Acetylcholine's Effect on Smooth Muscles
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Parasympatholytics
Parasympatholytics
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Atropine and Scopolamine
Atropine and Scopolamine
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Tertiary Ammonium Antimuscarinics
Tertiary Ammonium Antimuscarinics
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Quaternary Ammonium Antimuscarinics
Quaternary Ammonium Antimuscarinics
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Study Notes
Autonomic Nervous System
- The parasympathetic nervous system is affected by parasympathomimetics, which are drugs that mimic the action of acetylcholine (ACh) on cholinergic receptors.
Cholinergic Receptors
- There are two types of cholinergic receptors: muscarinic and nicotinic receptors.
- Muscarinic receptors:
- Blocked by atropine
- G-protein coupled receptors
- Subtypes: M1 (in autonomic ganglia), M2 (in the heart), M3 (in smooth muscles and secretory glands)
- Nicotinic receptors:
- Not blocked by atropine
- Ligand-gated ion channels
- Subtypes: Nm (in neuromuscular junction), Nn (in autonomic ganglia, adrenal medulla, and CNS)
Molecular Mechanisms and Signal Transduction of Cholinergic Receptors
- Nicotinic receptors: ligand-gated ion channels that increase permeability to Na+ and K+.
- Muscarinic receptors:
- M1, M3, and M5: Gq/11, stimulating phospholipase C, increasing [Ca++] and IP3
- M2 and M4: Gi, opening K+ channels, decreasing cAMP
Classification of Parasympathomimetics (Cholinergic Agonists)
- Direct-acting parasympathomimetics:
- Bind directly to receptors
- Examples: acetylcholine, methacholine, carbachol, bethanechol, pilocarpine, and muscarine
- Indirect-acting parasympathomimetics:
- Inhibit cholinesterase enzyme, increasing ACh levels
- Examples: physostigmine, neostigmine, and organophosphorus compounds
Pharmacology of Cholinergic Agonists
- Choline Esters (quaternary compounds):
- Pharmacological actions of ACh:
- Muscarinic actions
- Effect on the heart: bradycardia, decreased strength of contraction, and decreased A-V conduction
- Effect on smooth muscles: vasodilation and hypotension
- Pharmacological actions of ACh:
Parasympatholytics (Cholinergic Blocking Drugs)
- Antimuscarinic drugs that block muscarinic receptors, but not nicotinic receptors
- Natural occurring alkaloids: atropine and scopolamine
- Synthetic and semisynthetic:
- Tertiary ammonium drugs (cross BBB, affect CNS): benztropine, procyclidine, homatropine, cyclopentolate, and tropicamide
- Quaternary ammonium drugs (little CNS effects): ipratropium, tiotropium, propantheline, and glycopyrrolate
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Description
This quiz covers the pharmacology of drugs acting on the parasympathetic nervous system, specifically focusing on cholinergic receptors. Topics include types of cholinergic receptors such as muscarinic (M1, M2, M3) and nicotinic receptors.
