Intro
Agonistic Drug Effects:
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Antagonist Drug Effects:
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Part 1: Image-Mapped Tutorial
Part 2: Matching Self-Test
Part 3: Multiple-Choice Self-Test
11. Finally, a variety of drugs bind to neurotransmitter receptor sites, blocking the normal effects of these neurotransmitters. Direct antagonists have an affinity for the neurotransmitter's primary receptor site. This affinity results in competitive binding. The direct antagonist binds to the receptor site, preventing the neurotransmitter from doing so, but does not induce a postsynaptic potential. Indirect antagonists bind to an alternative site on the receptor. They are then able to block the effects of the neurotransmitter. Atropine, found in the belladonna plant, binds to the muscarinic subtype of acetylcholine receptors and blocks the binding of this neurotransmitter. This drug adversely affects memory. Curare blocks the nicotinic acetylcholine receptors at neuromuscular junctions, and causes paralysis and cessation of breathing.