Synaptic transmission

• Neurons communicate with each other through electrical signals within the neuron and chemical signals across the synapse.
• Dendrites receive information from other neurons, which then passes to the cell body.
• An electrical signal is sent down the length of the axon, known as an 'action potential'.
• When an electrical signal reaches the end of a neuron, it arrives at the terminal button.
• Tiny sacs called vesicles contain neurotransmitter molecules, which travel across the synaptic cleft to the next neuron in the chain, the postsynaptic neuron.
• When the transmitter crosses the synaptic cleft, it attaches to the next neurons receptor sites.
• The chemical message is turned back into an electrical impulse.
• The neurotransmitters left behind in the synaptic cleft are broken down into enzymes and reabsorbed by the presynaptic neuron so it can be reused.
• An electrical signal travels to the end of the presynaptic neuron, reaches the terminal button, and vesicles release a chemical called neurotransmitter.
• Neurotransmitter crosses synaptic cleft.
• Receptor sites on the postsynaptic neuron take up neurotransmitter.
• Chemical message is turned back into electrical impulse.
• Electrical impulse travels along postsynaptic neuron.
• Neurotransmitter left behind in synaptic cleft is broken down and reabsorbed.
• The effect of a neurotransmitter on the next neuron is either excitatory or inhibitory.
• An example of an excitatory neurotransmitter is adrenaline, which increases the postsynaptic neuron’s positive charge, making it more likely to fire.
• An example of an inhibitory neurotransmitter is serotonin, which increases the negative charge of the postsynaptic neuron, making it less likely to fire.
• A single neuron receives signals from many other neurons in a network, some are excitatory and some are inhibitory.
• Summation means the neuron fires when there are enough excitatory signals compared with inhibitory ones.