*Synaptic Transmission

• A synapse is the junction between the axon of one neuron and the dendrites of another.
• Synaptic transmission is the process of transmitting electrical impulses from the presynaptic to postsynaptic neuron.
• The 4 stages of Synaptic transmission are synthesis, release, receptor activation and inactivation
• Synthesis: Precursor chemicals are transported into the axon terminal in the presynaptic neuron. They are used to produce NTs which are then packaged into vesicles.
• Release: NTs are released into the synapse in response to electrical impulses
• Receptor activation: NTs diffuse across the synapse and bind to specific receptors on the post synaptic neuron.
• Inactivation: NTs then unbind and either go through reuptake into the presynaptic neuron via active transport where they are packaged into vesicles or they are broken down by the enzymes in the synapse
• 2 types of NT

  Excitatory and inhibitory
• When an excitatory NT binds to a receptor site in the post SN, it produces EPSP
• When an inhibitory NT binds to a receptor site in the post SN, it produces IPSP
• EPSP

  Excitatory post synaptic potential
• IPSP

  Inhibitory post synaptic potential
• Summation is when the post SN aggregates the overall amount of IPSP and EPSP to determine whether to fire or not.
• Excitation is when there is more EPSP than IPSP so there is an overall positive charge in the post SN. As a result it's more likely to fire
• Inhibition is when there is more IPSP than EPSP so there is an overall negative charge in the post SN. As a result it's less likely to fire