The drug-action atlas

Enter through a molecule, a synapse, or a brain circuit. Change the conditions and trace what happens next.

All learning models

Explore the system

Inside a working synapse

Follow an electrical signal into a chemical message, then trace its clearance and recycling.

Inside a working synapse

Animate the diagram

On a small screen, pan the diagram or increase zoom. Named controls provide the same exploration by keyboard.

Predict, then check

What passes through the postsynaptic ion channel?The neurotransmitterIonsAn intact vesicle

Exploration and predictions are practice. They do not award mastery or XP.

Sources and model limits

Original schematic. Positions show relationships; structures and concentrations are not to scale.

Julien's Primer of Drug Action · 15 · 2 · Inside a working synapse · PDF 26, 27, 30, 31 · 2.11, 2.17, 2.18

Diagram zoom

Original schematic. Positions show relationships; structures and concentrations are not to scale.

This combined teaching diagram compares monoamine clearance, an ionotropic response and glutamate–glia recycling. Most dopamine, norepinephrine and serotonin receptors signal through G proteins, rather than directly opening a channel.

Action potential arrives

Electrical activity reaches the axon terminal.

Transmission step

Inspect a structure

Presynaptic axon terminal

Contains vesicles, synthesis machinery, and intracellular enzymes.