Synaptic transmission

• Info is passed down the axon of the neuron as an electrical impulse known as action potential. Once the action potential reaches the end of the axon it needs to be transferred to another neuron or tissue.
• For info to be passed it must cross over a gap between the pre-synaptic neuron and the post-synaptic neuron - which is known as the synaptic gap. At the end of the neuron (in the axon terminal) are the synaptic vesicles which contain chemical messengers, known as neurotransmitters. When the electrical impulse (action potential) reaches these synaptic vesicles, they release their contents of neurotransmitters
• info must pass over a gap between pre and post synaptic neuron through the releasing of neurotransmitters
• Neurotransmitters then carry the signal across the synaptic gap. they bind to receptor sites on the post-synaptic cell that then becomes activated. Once the receptors have been activated, they either produce exicatory or inhibitory effects on the post synaptic cell.
• Some neurotransmitters are excitatory some are inhibitory- Excitatory neurotransmitters make the post-synaptic cell more likely to fire, whereas inhibitory transmitters make them less likely to fire.
• synapse- the point where one neuron (presynaptic) can send a chemical message to an adjacent neuron (postsynaptic)
• neurotransmitters- chemical messengers released by neurons, stimulating (or inhibiting) the development of an action potential in other (postsynaptic neurons)
• action potential arrives on the axon terminal, this causes the vesicles to merge the membrane of the presynaptic cell releasing the neurotransmitters
• action potential arrives at the axon terminal of previous neuron, causes a vesicle to move to the surface and neurotransmitters are released into the synaptic cleft, then they diffuse across the synaptic cleft and fuse with a receptor on the post synaptic neuron, if they are excitatory neurotransmitters, then it will increase positive charge of the post synaptic neuron, meaning the post synaptic neuron is more likely to fire,
• summation- combined effect of all neurotransmitters on postsynaptic neuron that determines whether or not it is likely to fire