When the electrical impulse (action potential) reaches the axon terminal, it cannot directly cross the synaptic gap to stimulate the next neuron. Instead, the impulse causes the release of chemical messengers called neurotransmitters from synaptic vesicles in the axon terminal. These neurotransmitters diffuse across the synaptic gap and bind to receptor molecules on the membrane of the next neuron. This binding stimulates the second neuron to transmit a new electrical impulse along its axon, effectively carrying the signal from one neuron to the next. Key points of the process:
- The electrical impulse travels down the axon to the axon terminal.
- Arrival of the impulse triggers calcium ions to enter the axon terminal.
- This causes synaptic vesicles to release neurotransmitters into the synaptic gap.
- Neurotransmitters cross the gap and bind to receptors on the postsynaptic neuron.
- This binding converts the chemical signal back into an electrical impulse in the next neuron.
Thus, the electrical impulse is converted into a chemical signal to bridge the synaptic gap and then converted back to an electrical signal in the receiving neuron.
