Neuronal Signaling and Synaptic Transmission Vocabulary

Vocabulary flashcards focusing on key terminology related to electrical and chemical synaptic transmission, neurotransmitters, and receptor mechanisms from the lecture notes.

Electrochemical Gradient

The simultaneous electrical and chemical forces acting upon ions across a neuron's cell membrane.

Resting Membrane Potential

The average electrical charge inside a neuron at rest relative to the extracellular space, which is approximately $-70\,mV$.

Leak Channels

Ion channels in the cell membrane that are open all the time, allowing very specific ions to continuously pass through.

Action Potential

An all-or-nothing electrical response that begins at the axon hillock and travels down the length of the axon.

Depolarization Phase

The phase of an action potential where the cell membrane charge becomes more positive after reaching the threshold of $-55\,mV$, peaking around $+40\,mV$.

Repolarization Phase

The phase of an action potential during which the membrane potential returns back toward a negative charge.

Hyperpolarization Phase

The phase of an action potential where the membrane potential temporarily overshoots the resting charge, becoming more negative than $-70\,mV$.

Spatial Summation

The combined effect of multiple postsynaptic potentials that occur close together physically on their target to create a larger response.

Temporal Summation

The combined effect of postsynaptic potentials activated at similar points in time, causing their individual effects to add up.

Electrical Synapses

Direct connections between presynaptic and postsynaptic neurons where direct changes in electricity occur near-instantaneously via shared cytoplasm.

Connexon

A structure composed of several transmembrane proteins that links presynaptic and postsynaptic cells together at an electrical synapse.

Gap Junction

The physical bridge and small distance connecting two separate cells in an electrical synapse, allowing ions and small chemical messengers to pass between them.

Chemical Synapses

Indirect connections where presynaptic and postsynaptic cells are physically disconnected by a gap and rely on neurotransmitters to transmit signals.

Vesicles

Small bisphospholipid bilayer spheres within the axon terminal that package and store neurotransmitters prior to release.

v-SNARE

A vesicle protein that binds to a target protein on the axon membrane in the presence of calcium to facilitate neurotransmitter release.

t-SNARE

A target protein on the axon terminal membrane that combines with a v-SNARE to form a SNARE complex.

Ionotropic Receptors

Ligand-gated ion channels that open directly upon binding a neurotransmitter, allowing fast flow of ions across the membrane.

Metabotropic Receptors

G protein-coupled receptors that indirectly cause a cascade of cellular changes through G proteins and second messengers when bound by a neurotransmitter.

Agonist

Any chemical that binds to the active site of a receptor and activates it to trigger a biological response.

Reuptake

The clearance mechanism in which neurotransmitters are recycled out of the synaptic gap and taken back up into the presynaptic neuron or astrocytes.

Glutamate

The main excitatory neurotransmitter in the human nervous system, commonly acting on ionotropic receptors such as AMPA and NMDA.

GABA

The primary inhibitory neurotransmitter in the human nervous system, derived from glutamate, which induces hyperpolarization in postsynaptic targets.

Acetylcholine

A neurotransmitter that drives muscle movements in the peripheral nervous system and regulates memory, wakefulness, and attention in the central nervous system.

Dopamine

A neurotransmitter produced in the substantia nigra and ventral tegmentum that is linked to motor coordination, reward, motivation, and learning signals.

Norepinephrine

A neurotransmitter produced in the locus coeruleus that drives sympathetic peripheral responses and regulates emotion, arousal, and vigilance in the brain.

Serotonin

A neurotransmitter produced exclusively within the raphe nuclei that is heavily involved in regulating mood and sleep-wake cycles.

GLP-1

A satiety-signaling peptide released after eating that targets receptors in regions like the hypothalamus to slow intestinal movement and induce feelings of fullness.