Neurotransmitters of the CNS Flashcards
(32 cards)
What foundational experiment demonstrated chemical transmission between nerves?
Otto Loewi’s frog heart experiment; showed a chemical released from one nerve affected another heart.
What is the Neuron Doctrine?
Neurons are discrete cells, separated by synapses; information flows unidirectionally (dendrite → axon).
Outline the steps of synaptic transmission.
Action potential arrives at presynaptic terminal.
Ca²⁺ influx → neurotransmitter release from vesicles into synaptic gap.
Neurotransmitters bind to postsynaptic receptors.
Postsynaptic membrane potential changes.
Differentiate excitatory vs. inhibitory postsynaptic potentials.
Excitatory (EPSP): Depolarization, ↑ firing likelihood.
Inhibitory (IPSP): Hyperpolarization, ↓ firing likelihood.
How is stimulus intensity encoded by neurons?
By the firing rate or frequency of action potentials (Rate Law).
Explain temporal and spatial summation.
Temporal: Rapid inputs from few neurons summate.
Spatial: Synchronized inputs from multiple synapses summate in a small region.
Both can lead to firing threshold.
List the major classes of neurotransmitters.
Amino Acids, Cholines, Monoamines (Catecholamines, Indolamines), Peptides, Lipids, Nucleosides.
What are the key amino acid neurotransmitters, receptors and effects?
Glutamate: NMDA, AMPA, mGlu, kainate receptors → neural signaling, learning, memory.
GABA: GABA-A, GABA-B receptors → neural inhibition.
How are GABAergic neurons identified?
By glutamate decarboxylase (GAD) enzyme.
What are the key choline neurotransmitters, receptors and effects?
Acetylcholine (ACh): Nicotinic, muscarinic receptors → muscle control, autonomic signaling, learning, memory.
What is ACh synthesized from, and where are cholinergic neurons located?
From choline + acetyl coenzyme A (CoA); located in basal forebrain + brainstem.
How are cholinergic neurons identified?
By choline acetyltransferase (ChAT) enzyme.
What are the key catecholamine neurotransmitters, receptors and effects?
Dopamine (DA): D1-5 receptors → reward signaling, movement.
Noradrenaline (NA) / Norepinephrine (NE): Alpha, beta adrenergic receptors → autonomic signals, attention, arousal.
From what precursor are catecholamines derived?
Tyrosine.
Origin and pathways of dopamine neurons.
Substantia nigra → Mesostriatal pathway (movement).
Ventral Tegmental Area (VTA) → Mesolimbocortical pathway (reward, learning).
Where do noradrenergic neurons originate?
Locus Coeruleus (CNS).
How are dopaminergic and noradrenergic neurons identified?
Via enzymes in their synthetic pathway:
Tyrosine Hydroxylase
Dopamine Beta-Hydroxylase (for noradrenergic).
What are the key indolamine neurotransmitters, receptors and effects?
Serotonin (5HT): 5HT receptors → mood, sleep, perception.
From what is serotonin produced, and where are serotonergic neurons located?
Produced from tryptophan; located in Raphe nuclei (brainstem).
How are serotonergic neurons identified?
By tryptophan hydroxylase (TH) enzyme.
What are the key opioid neurotransmitters, receptors, and effects?
Endorphins, enkephalins, dynorphins.
μ-, δ-, κ-opioid receptors.
Pain/analgesia, pleasure/hedonia.
What are the key endocannabinoid neurotransmitters, receptors, and effects?
Anandamide.
Cannabinoid receptors.
Pleasure/hedonia, appetite.
What is immunolabelling used for in neuroscience?
Identifying specific neurons and receptors by visualizing target proteins/enzymes using antibodies.
Explain ‘double labeling’ in immunolabelling.
Uses different primary antibodies to target two distinct antigens, visualized by distinct fluorescent secondary antibodies, to show co-localization.
