Synaptic transmission

• Pre-synaptic axon terminal


  • Contains the neurotransmitters (Chemical messengers)
• Synaptic cleft


  • The gap between the two neurons, typically above 20-30 nanometres wide
• Post-synaptic neuron


  • Contains the sites for receptors that receive signals
• Synapses are essential for systematic neural activity
• Synapses play a key role in a variety of cognitive functions, including learning and memory formation
• Chemical Synapse


  A connection between two neurons, where nerve impulses are transmitted by a neurotransmitter from the axon of a presynaptic (sending) neuron to the dendrites of the post-synaptic (receiving) neuron
• Chemical Synapse


  • The gap between neurons is called the synaptic cleft or gap
• Chemical Synaptic Transmission


  Action potential (electrical impulse) triggers the synaptic vesicles of the pre-synaptic neuron to release neurotransmitters (a chemical message)
• Electrical Synapse


  A direct physical connection between the presynaptic and the postsynaptic neuron, allowing ions to flow directly from one neuron to the other
• Electrical Synapse


  • The connection takes the form of a gap junction, which is a channel that allows ions to flow directly from the presynaptic cell to the postsynaptic cell
• Gap Junctions


  • Contain paired channels in the pre and postsynaptic membranes, forming pores that are larger than those of the voltage-gated ion channels in Chemical Synapses, allowing substances to diffuse between the neurons
• Electrical synapses are less common than chemical synapses in vertebrates
• In electrical synapses, an electrical change in one neuron is immediately reflected in the other
• Electrical synapses are different from chemical synapses as there is a direct physical connection between the presynaptic and postsynaptic neuron