Neurotransmitters (synapses, signaling & neurotransmission explained)

Neurotransmitter

Chemical messenger that transmits signals across a synapse from one neuron to another.

Synapse

The junction between two neurons where neurotransmission occurs.

Chemical Synapse

A synapse where neurotransmitters are released from vesicles and bind to receptors on the next neuron.

Electrical Synapse

A fast, less common synapse where ions pass directly between neurons through gap junctions.

Neurotransmission

The process of sending signals between neurons using neurotransmitters

Action Potential

An electrical signal traveling down a neuron’s axon that triggers neurotransmitter release.

Calcium Influx

The entry of Ca²⁺ into the neuron terminal, triggering vesicle fusion and neurotransmitter release.

Reuptake

The process of neurotransmitters being reabsorbed into the presynaptic neuron to stop signaling.

Enzymatic Degradation

Breaking down neurotransmitters with enzymes to stop their action.

Excitatory Neurotransmitte

Increases the likelihood that the postsynaptic neuron will fire (example: Glutamate).

Inhibitory Neurotransmitter

Decreases the likelihood that the postsynaptic neuron will fire (example: GABA).

Glutamate

The main excitatory neurotransmitter in the brain; important for learning and memory.

GABA

The main inhibitory neurotransmitter in the brain; calms neuronal activity.

Acetylcholine

Involved in muscle movement and memory.

Dopamine

Regulates reward, motivation, and movement; linked to Parkinson’s and addiction.

Serotonin

Regulates mood, sleep, and appetite; linked to depression and anxiety.

Norepinephrine

Involved in alertness, attention, and the fight-or-flight response.

Ionotropic Receptor

A receptor that directly opens an ion channel for fast signaling.

Metabotropic Receptor

A receptor that triggers slower, long-lasting effects through signaling cascades.

Signal Termination

The stopping of neurotransmitter action by reuptake, breakdown, or diffusion.