Describe the process of synaptic transmission
- Information is passed down the axon of the neuron through electrical impulses known as an action potential. When a neuron is in resting state, the inside of the cell is negatively charged compared to the outside.
2. When a neuron is activated by a stimulus, the inside of the cell becomes positively charged for a split-second causing an action potential.
3. This creates an electrical impulse that travels down the axon to the end of the neuron, where it must cross a gap between the pre-and post-synaptic neuron, known as the synapse.
4. When the electrical impulse reaches the end of the neuron (the presynaptic terminal) it triggers the release of neurotransmitters from synaptic vessels. Neurotransmitters then carry the signal across the synaptic gap and have a specific molecular structure that binds to post-synaptic receptor sites, like a lock and key.
5. Neurotransmitters generally have an excitatory or inhibiting effect on the neighbouring neuron. Excitatory neurotransmitters increase the likelihood that an electrical impulse will be triggered causing an EPSP whereas inhibitory neurotransmitters decrease the likelihood of an electrical impulse being triggered causing an IPSP.
6. The likelihood of the cell firing is determined by the net-result of summing up excitatory and inhibitory synaptic input– the summation. if the net result of ESPs is greater than the net result of IPSPs, the cell is more likely to fire.
