Communication Between Neurons

Overview

• Communication between neurons involves a sequence of events triggered by an electrical impulse known as an action potential.

Action Potential

• The action potential travels along the axon of the presynaptic neuron towards the axon terminal but cannot cross the synaptic space.

Vesicle Fusion and Neurotransmitter Release

• On reaching the axon terminal, the action potential causes vesicles (membranous sacs) to move towards and fuse with the membrane of the axon terminal.
• This fusion releases the contents of the vesicles into the synaptic space.
• The released molecules are chemicals known as neurotransmitters.

Neurotransmitter Binding

• Neurotransmitters drift across the synaptic space and bind to receptors on the postsynaptic neuron.
• Binding can trigger an action potential in the postsynaptic neuron, moving the electrical signal towards its cell body.

Termination of Signal

• After relaying the message, neurotransmitters release from receptors back into the synaptic space.
• Some neurotransmitters are degraded by enzymes in the synaptic space.
• Others are taken back into the presynaptic neuron via transporter proteins.

Recycling of Neurotransmitters

• Neurotransmitters taken back into the presynaptic neuron are repackaged into vesicles.
• These vesicles are ready to be released again the next time an action potential reaches the axon terminal.

Process Repetition

• This communication process repeats every time an action potential arrives at the axon terminal of the presynaptic neuron.