Fast doors and slow keypads: ionotropic and metabotropic receptors
Explains what happens after a receptor is activated — an instant ion flow, or a slower chain that can change the cell for a long time.
Where this fitsConnects to 1 · Unlocks 3
- Connects to
- Locks and keys: receptor specificity, agonists and antagonists — Picks up right after the key turns.
- Unlocks
- Dopamine: receptor families, clearance and pathways — All dopamine receptors are metabotropic.
- Glutamate and GABA: the brain's accelerator and brake — NMDA, AMPA and GABA-A are ionotropic.
- Acetylcholine: nicotinic, muscarinic and AChE — Nicotinic is ionotropic; muscarinic is metabotropic.
Walk through
Ionotropic: the door with a lock
The receptor itself is the channel. Binding opens it, and ions flow at once — depolarizing (excitatory) or hyperpolarizing (inhibitory). It's built from subunits that change how it responds.
Analogy and worked example
Analogy: Ionotropic: a door with a lock — turn the key and it swings open instantly. Metabotropic: a Wi-Fi keypad — enter the code and it sends a signal to unlock a separate door, and can also message the building office to change the rules for the future.
A drug causes a response within milliseconds that ends almost as soon as it's washed out. Which receptor type is it likely acting on?
- Milliseconds points to direct ion flow.
Tip: the ← and → keys move through the lesson.
Full lesson: Receptor signaling mechanisms