Society and the Brain lesson 5

Electrical synapse

A fast, bidirectional synapse that allows direct flow of ions/molecules between two connected cells without neurotransmitter.

Chemical synapse

A slower, unidirectional synapse that relies on neurotransmitter release from the presynaptic cell binding to receptors on the postsynaptic cell.

Synaptic vesicle

A membrane-bound sac in the presynaptic terminal that stores neurotransmitter before release.

SNARE proteins

Proteins (including synaptobrevin on the vesicle) that interact between the vesicle and presynaptic membrane to dock the vesicle in place for release.

Synaptobrevin

The SNARE protein located on the synaptic vesicle itself

Synaptotagmin

The calcium sensor protein; when Ca²⁺ binds to it, this triggers SNARE proteins to pull the vesicle into the membrane for release.

Voltage-gated Ca²⁺ channel

A channel in the presynaptic membrane that opens in response to depolarization (from an arriving action potential), allowing Ca²⁺ to flow in from the extracellular fluid.

Exocytosis

The process by which a vesicle fuses with the membrane and releases its contents (neurotransmitter) into the synaptic cleft.

Acetylcholine (ACh)

The neurotransmitter at the vertebrate neuromuscular junction; broken down by acetylcholinesterase (AChE) after release.

Acetylcholinesterase (AChE)

The enzyme that breaks down acetylcholine into choline and acetic acid after it has acted in the synapse.

Glutamate

The major excitatory neurotransmitter in the central nervous system.

GABA

The major inhibitory neurotransmitter in the CNS (in adults).

Norepinephrine (noradrenaline)

A neurotransmitter in the central and peripheral nervous system, mainly excitatory, associated with the fight-or-flight response.

Substance P

A neurotransmitter associated with pain transmission.