Here's how they work:
1. Action Potential Arrives: An electrical signal (action potential) travels down the axon of a neuron.
2. Neurotransmitter Release: The action potential reaches the axon terminal and triggers the release of neurotransmitters from vesicles into the synaptic cleft (the gap between neurons).
3. Neurotransmitter Binding: The neurotransmitters diffuse across the synaptic cleft and bind to specific receptor proteins on the postsynaptic neuron's membrane.
4. Signal Transduction: This binding initiates a change in the postsynaptic neuron, either excitatory (making the neuron more likely to fire) or inhibitory (making the neuron less likely to fire).
5. Neurotransmitter Removal: To stop the signal, neurotransmitters are either broken down by enzymes in the synaptic cleft, or reabsorbed back into the presynaptic neuron (reuptake).
Examples of common neurotransmitters:
* Acetylcholine: Involved in muscle contraction, learning, and memory.
* Dopamine: Plays a role in reward, motivation, and movement.
* Serotonin: Affects mood, sleep, appetite, and learning.
* Norepinephrine: Regulates alertness, arousal, and attention.
* GABA: The primary inhibitory neurotransmitter in the brain.
* Glutamate: The primary excitatory neurotransmitter in the brain.
In summary: Neurotransmitters are chemical messengers that allow communication between neurons at synapses. They play a crucial role in all aspects of nervous system function, including thought, emotion, behavior, and movement.
