3.2 Neurotransmitters Differ in Their Chemical Composition and Anatomical Distribution Flashcards
What are the general criteria for a substance to act as a neurotransmitter?
1) It can be synthesized by presynaptic neurons and stored in axon terminals.
2) It is released when action potentials reach the terminals.
3) It is recognized by specific receptors on the postsynaptic membrane.
4) It causes changes in the postsynaptic cell.
5) Blocking its release interferes with the presynaptic cell’s ability to affect the postsynaptic cell.
Name the four major families of neurotransmitters.
1) Amino Acids
2) Amines
3) Neuropeptides
4) Gases
Give examples of amino acid neurotransmitters.
Gamma-aminobutyric acid (GABA)
Glutamate
Glycine
Histamine
What are the subfamilies and examples of amine neurotransmitters?
Quaternary amines: Acetylcholine (ACh)
Monoamines:
Catecholamines: Norepinephrine (NE), epinephrine (adrenaline), dopamine (DA)
Indoleamines: Serotonin (5-HT), melatonin
Name examples of neuropeptides.
Opioid peptides:
Enkephalins: Met-enkephalin, Leu-enkephalin
Endorphins: Beta-endorphin
Dynorphins: Dynorphin A
Other neuropeptides:
Oxytocin
Substance P
Cholecystokinin (CCK)
Vasopressin
Neuropeptide Y (NPY)
Name examples of gasotransmitters.
Nitric oxide
Carbon monoxide
Which amino acid neurotransmitter is the most widespread excitatory transmitter in the brain?
Glutamate
What are the subtypes of glutamate receptors?
Ionotropic: AMPA, kainate, NMDA
Metabotropic: mGluR (metabotropic glutamate receptors)
Which amino acid neurotransmitter is the most widespread inhibitory transmitter in the brain?
Gamma-aminobutyric acid (GABA)
What are the subtypes of GABA receptors and their functions?
GABAA: Ionotropic, rapid inhibition via Cl⁻ ion influx; reduces anxiety and seizure activity.
GABAB: Metabotropic, slower inhibitory effects; may treat pain and mood disorders.
Where are cholinergic neurons primarily found, and what is their function?
Found in the basal forebrain.
Project to the cerebral cortex, amygdala, and hippocampus.
Play a role in learning, memory, and are implicated in Alzheimer’s disease.
What are the two families of acetylcholine (ACh) receptors?
-Nicotinic (ionotropic): Excitatory, drive muscle contractions.
-Muscarinic (metabotropic): Can be excitatory or inhibitory, involved in cognitive processes.
Name the functions and receptor subtypes for dopamine (DA).
Functions: Motor function, reward, higher cognition.
Receptors: D1–D5 (all metabotropic).
What are the functions of norepinephrine (NE) in the brain?
Provides alerting and arousing functions.
Plays a role in fight-or-flight responses.
What are the serotonin receptor subfamilies and their roles?
5-HT1: Five members with various distributions.
5-HT2: Mood, sleep, higher cognition.
5-HT3–5-HT7: Includes roles in nausea and metabotropic functions (except 5-HT3).
