Synapse Cross-Section Simulator (2D)

Stimulus

Stimulus strength 50

Auto-fire rate 1.0 Hz

Neurotransmitter

Resting potential — awaiting stimulus.

Live Readout

Membrane potential

−70 mV

Vesicles released

Postsynaptic response

+0.0 mV

Response type

—

How it works

An action potential arriving at the axon terminal depolarizes the presynaptic membrane, opening voltage-gated Ca²⁺ channels. The resulting calcium influx triggers synaptic vesicles docked at the membrane to fuse with it and dump their neurotransmitter into the synaptic cleft.

Neurotransmitter molecules diffuse across the cleft and bind postsynaptic receptors. Glutamate opens cation channels, depolarizing the postsynaptic membrane (an EPSP — excitatory postsynaptic potential). GABA opens Cl⁻/K⁺ channels, pushing the membrane further negative (an IPSP — inhibitory postsynaptic potential). Stronger stimulus recruits more vesicles and a larger response; unbound transmitter is cleared and the potential relaxes back toward the −70 mV resting level.

Presynaptic terminal Ca²⁺ ion Glutamate (excitatory) GABA (inhibitory)