Neurotransmitters and Receptors
Chemical messengers
What neurotransmitters do
Neurotransmitters are molecules released by neurons to influence other cells. Some common examples include glutamate, GABA, dopamine, serotonin, acetylcholine, and norepinephrine. Different neurotransmitters often play different roles, but their effects also depend on which receptor they bind to.
Examples of neurotransmitters
| Neurotransmitter | Common association |
|---|---|
| Glutamate | Major excitatory signal in the brain |
| GABA | Major inhibitory signal in the brain |
| Dopamine | Movement, motivation, reward |
| Serotonin | Mood, sleep, appetite |
| Acetylcholine | Muscle control and attention |
Receptors
Receptors are proteins that detect neurotransmitters and trigger a response. Some receptors are ion channels that open quickly when a neurotransmitter binds. Others work through slower chemical signaling inside the cell. The same neurotransmitter can have different effects in different cells because receptor type matters.
Two broad receptor types
Ionotropic receptors
- Fast action
- Open an ion channel directly
Metabotropic receptors
- Slower action
- Trigger internal signaling pathways
Beginner tip
Do not memorize neurotransmitters as simple labels like 'good' or 'bad'; their effects depend on context, receptor type, and circuit.
Which neurotransmitter is most commonly inhibitory in the brain?
GABA is the main inhibitory neurotransmitter in the brain.
Correct answer: GABA
Why can the same neurotransmitter have different effects in different cells?
Receptor type determines the response.
Correct answer: because different cells express different receptors