4 - Foundations of Neuroscience: Synapses and the Role of Neurotransmitters (Vocabulary)

A set of vocabulary flashcards covering neurons, synapses, neurotransmitters, receptors, and signaling mechanisms.

Neuron

The basic functional unit of the nervous system; processes and transmits information via electrical impulses and synapses.

Glia

Non-neuronal support cells that provide structural/metabolic support, electrical insulation, guidance of connections, and signaling; about 10x more abundant than neurons.

Unipolar neuron

A neuron with a single axonal process; common example in invertebrates.

Bipolar neuron

A neuron with two processes (usually one axon and one dendrite); example includes retinal bipolar cells.

Pseudo-unipolar neuron

A neuron with a single axon that splits into two branches; typical of dorsal root ganglion cells.

Multipolar neuron

A neuron with multiple axonal processes; includes many motor and cortical neurons (e.g., Purkinje, pyramidal).

Golgi type I

Projection neurons with long axons that connect distant brain regions.

Golgi type II

Local circuit neurons with short axons that connect nearby neurons.

Dendrite

Branch-like extensions of a neuron that receive inputs from other neurons.

Axon hillock

The region where action potentials are initiated.

Axon terminal (synaptic bouton

The end of the axon where neurotransmitters are released into the synapse.

Synapse

The junction through which a neuron communicates with another cell, via electrical or chemical signals.

Electrical synapse (gap junction)

A fast, bidirectional synapse where ions pass directly between cells via gap junctions.

Gap junction

Channels formed by connexins that allow direct cytoplasmic transfer between adjacent cells.

Connexin

Protein subunits that assemble into connexons forming gap junction channels.

Connexon

Half-channel of a gap junction; two connexons form a complete gap junction channel.

Neurotransmitter

Chemical messenger released from the presynaptic terminal that diffuses across the synaptic cleft to bind receptors on the postsynaptic cell.

Receptor

A membrane protein that recognizes a neurotransmitter and initiates intracellular signaling.

Ionotropic receptor

A receptor that directly opens an ion channel upon transmitter binding, causing rapid synaptic transmission.

Metabotropic receptor

A receptor that activates G-proteins and secondary messengers to influence signaling; slower, longer-lasting effects.

AMPA receptor

A fast excitatory ionotropic glutamate receptor mediating Na+ influx and depolarization.

NMDA receptor

A voltage- and ligand-gated ionotropic glutamate receptor involved in Ca2+ influx and synaptic plasticity.

Kainate receptor

An ionotropic glutamate receptor contributing to excitatory transmission.

GABA_A receptor

An inhibitory ionotropic receptor that conducts Cl- to hyperpolarize the cell.

Glycine receptor

An inhibitory ionotropic receptor that conducts Cl- in the CNS.

Nicotinic acetylcholine receptor

A fast, excitatory ionotropic receptor for acetylcholine, permeable to Na+ and K+.

Glutamate

Major excitatory neurotransmitter in the CNS.

GABA

Main inhibitory neurotransmitter in the CNS; GABA_A is ionotropic while others are metabotropic.

Dopamine

Monoamine neurotransmitter involved in reward, movement, and motivation.

Norepinephrine (noradrenaline)

Monoamine involved in arousal, attention, and autonomic responses.

5-HT (serotonin)

Monoamine involved in mood, appetite, and sleep; multiple receptor subtypes exist.

Acetylcholine (ACh)

Neurotransmitter at neuromuscular junctions and in the CNS; acts on nicotinic (ionotropic) and muscarinic (metabotropic) receptors.

Endorphin

Opioid peptide neurotransmitter involved in analgesia and reward.

Enkephalin

Opioid peptide involved in pain modulation and other CNS functions.

Substance P

Tachykinin neuropeptide involved in pain signaling.

Reuptake

Reabsorption of neurotransmitter back into the presynaptic neuron to terminate signaling.

Enzymatic breakdown

Destruction of neurotransmitters in the synaptic cleft by enzymes to terminate signaling.

Exocytosis

Release of neurotransmitter-containing vesicles into the synaptic cleft via vesicle fusion.

Calcium-triggered release

Ca2+ influx into the presynaptic terminal triggers vesicle fusion and transmitter release.

Postsynaptic potential

Electrical change in the postsynaptic cell following neurotransmitter receptor activation.

Receptor subtypes

Different variants of a receptor for the same neurotransmitter (e.g., AMPA vs NMDA; GABAA vs GABAB).

Presynaptic receptor

Receptors on the presynaptic terminal that modulate transmitter release (e.g., autoreceptors).

Synaptic vesicle

Vesicles in the presynaptic terminal that store neurotransmitters before release.

Postsynaptic receptor activation

Binding of neurotransmitter to postsynaptic receptors, triggering intracellular signaling.

Ion flux

Movement of ions across the membrane that changes the membrane potential during neurotransmission.

Excitatory transmission

Neurotransmission that increases the likelihood of the postsynaptic neuron firing (e.g., glutamate via AMPA/NMDA).

Inhibitory transmission

Neurotransmission that decreases the likelihood of firing (e.g., GABA_A–mediated Cl- influx).