Neurotransmitters are chemical messengers that allow neurons to communicate. Understanding their usual functions—and how disrupted signaling may be associated with disease—provides a foundation for learning how nervous-system drugs work.
When a signal causes neurotransmitter release, molecules cross the cleft and bind to receptors. Depending on the transmitter, receptor, and target cell, the result may be activation, inhibition, or another change in the receiving cell's activity.
All flashcards
What happens at a chemical synapse?
Neurotransmitters released from a presynaptic terminal cross the synaptic cleft and bind receptors on a receiving cell.
How do GABA and glutamate generally affect neuronal activity?
GABA is primarily inhibitory, whereas glutamate is the primary excitatory neurotransmitter.
What distinguishes cholinergic from adrenergic signaling?
Cholinergic nerves release acetylcholine; norepinephrine and epinephrine produce many effects through adrenergic receptors.
What is the difference between a direct-acting and an indirect-acting parasympathomimetic?
A direct-acting drug stimulates cholinergic receptors; an indirect-acting drug increases synaptic acetylcholine, often by inhibiting its breakdown.
Why does a drug's autonomic effect depend on the tissue it affects?
Effects depend on the drug's receptor targets and which receptors are expressed by the target tissue.
Quiz questions
What is a typical effect of activating alpha-2 adrenergic receptors?Answer: Inhibition of norepinephrine release.
How does an agonist differ from an antagonist?Answer: An agonist activates receptor signaling; an antagonist blocks receptor activation.
Which statement describes an indirect-acting parasympathomimetic?Answer: It increases synaptic acetylcholine, often by reducing its breakdown.
What is the primary action of an anticholinergic drug?Answer: It blocks the effects of acetylcholine.
Which response is associated with beta-2 adrenergic receptor activation?Answer: Smooth-muscle relaxation.
Based on Pharmacology for Nurses by Tina Barbour-Taylor, Leah Mueller (Sabato), Donna Paris, Dorie Weaver (OpenStax), licensed CC BY 4.0. Adapted into a summary, flashcards and quizzes.