Topic 11.2 · Synapses: The Neurotransmitters Table

Vocabulary flashcards reviewing neurotransmitter classifications, receptor types, modes of action, pharmacological agents, and physiological functions from the Topic 11.2 Synapses exam review.

Nicotinic acetylcholine receptor

A fast, ionotropic receptor acting as a $\text{Na}^+$ & $\text{K}^+$ channel; excitatory at the NMJ & CNS, stimulated by the agonist nicotine and blocked by the antagonist curare.

Muscarinic acetylcholine receptor

A slow, metabotropic GPCR stimulated by the agonist muscarine; functions in the PNS to promote rest/relax and slow the heart.

Alpha-1,2 adrenergic receptors

Slow, metabotropic GPCR ($\text{IP}_3/\text{Ca}^{2+}$) receptors for norepinephrine that mediate fight-or-flight responses in the SNS.

Beta-1 adrenergic receptor

A slow, metabotropic GPCR (cAMP) receptor for norepinephrine targeted by beta blockers; functions in the SNS to increase heart rate.

Dopamine

A slow neurotransmitter with mostly excitatory effects that functions in reward; its reuptake is affected by cocaine, meth, and Adderall.

Serotonin

A slow neurotransmitter with mostly inhibitory effects that promotes positive mood; its reuptake is targeted by antidepressants.

Glutamate

The main excitatory neurotransmitter in the CNS; acts fast via AMPA and NMDA receptors ($\text{Na}^+/\text{K}^+$, plus $\text{Ca}^{2+}$ for NMDA) and is antagonized by ketamine.

Glycine

A fast inhibitory neurotransmitter in the CNS that acts through a $\text{Cl}^-$ channel.

GABA

A fast inhibitory neurotransmitter in the CNS that acts through a $\text{Cl}^-$ channel.

Amino acid neurotransmitters

Transmitters (e.g., glutamate, glycine, GABA) that run most CNS synapses and are typically fast / ionotropic.

Amine neurotransmitters

Transmitters (e.g., dopamine, serotonin, norepinephrine) that are slow / metabotropic and characterized by few neurons with many synapses.

Peptide neurotransmitters

A class of neurotransmitters that are rare and typically co-released with other transmitters.

Ketamine

A drug that acts as an NMDA receptor antagonist, blocking glutamate transmission.

Curare

A drug that acts as an antagonist at nicotinic acetylcholine receptors.

Beta blockers

A class of drugs that target beta-1 adrenergic GPCR (cAMP) receptors to block norepinephrine-mediated heart rate increases.

Receptor-dependent transmitter action

The principle that while each synapse is strictly excitatory OR inhibitory, a single neurotransmitter can carry out both functions depending on the receptor (e.g., ACh excites muscle via nicotinic receptors but slows the heart via muscarinic receptors).