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A neuron transmits a signal electrically along its own axon and chemically across the gap (synapse) to the next neuron. At rest, the inside of a neuron is negatively charged relative to the outside (resting membrane potential of about −70 mV), maintained by ion pumps. A stimulus causes sodium channels to open, allowing Na⁺ ions to rush in and reverse the local charge — this is the action potential. The depolarisation propagates along the axon like a wave, with the myelin sheath acting as insulation to speed transmission (saltatory conduction). When the action potential reaches the axon terminal, it triggers voltage-gated calcium channels to open. Calcium influx causes synaptic vesicles to fuse with the membrane and release neurotransmitters (such as acetylcholine, dopamine, or glutamate) into the synaptic cleft. These bind to receptors on the receiving neuron's dendrites, opening ion channels and either exciting or inhibiting the next neuron.
answered by Omniscientia Team · 176 words · 18 Mar 2026