Synaptic transmission

• Neurons communicate within groups known as neural networks
• Each neuron is separated from the next by a tiny gap called the synapse
• Signals within neurons are transmitted electrically

  When a neuron receives a stimulus the inside of the cell becomes postively charged and causes an action potential to occur.

  This creates an electrical impulse that travels down the axon towards the end of the neuron
• Signals between neurons are transmitted chemically across the synapse
• When the electrical impulse reaches the end of the neuron (terminal) it triggers the release of neurotransmitters from tiny sacs called synaptic vesicles
• Neurotransmitters are brain chemicals that communicate information throughout the brain and body (chemical messangers)
• Neurotransmitters pass information when they are released from one neuron (pre-synaptic neuron) by diffusing across the synapse to the next neuron (post-synaptic neuron)
• Once a neuron crosses the gap, it is taken up by the postsynaptic receptor site (dendrites of the next neuron)
• There are many different types of neurotransmitters each with its own specific molecular structure that fits into a post synaptic receptor site, like a lock and key
• Excitatory neurotransmitters stimulate neurons by increasing its positive charge and making it more likely to fire
• Excitatory neurotransmitter examples - adrenaline and noradrenaline
• Inhibitory neurotransmitters cause the neuron to be more negatively charged and less likely to fire. Therefore they balance mood and are easily depleted then the excitatory neurotransmitters are overactive
• Inhibitory neurotransmitter examples - GABA, serotonin
• The post synaptic neuron receives inputs from many neurotransmitters, both excitatory and inhibitory
• Inhibitory and excitatory influences are summed (summations) and if the net effect is inhibitory, the neuron is less likely to fire

  If net effect is excitatory then the neuron is more likely to fire