Synaptic transmission

• Messages in the brain are sent by using electrical impulses and chemicals called neurotransmitters
• What’s missing - post synaptic neuron

  
• What’s missing - synaptic cleft

  
• What’s missing - pre synaptic neuron

  
• What’s missing - action potential/nerve impulse

  
• What’s missing - receptersite

  
• What’s missing- neurotransmitters

  
• What’s missing- axon terminal

  
• What’s happening here - reuptake

  
• What’s this - ventricle

  
• What’s this symbolising - enzyme

  
• Neurotransmitters are chemical

  messengers that act between neurons
• The postsynaptic neuron will receive both excitatory

  and inhibitory inputs.
• The effect of the neurotransmitters on the postsynaptic

  neuron depends on the summation or adding together of signals.
• Summation could be over time – temporal summation,

  Or over space – spatial summation.
• The electrical impulse in the presynaptic neuron cannot "jump" across the

  synaptic gap, so signals have to be transmitted chemically
• step 1: When the action potential reaches the terminal buttons it triggers the release

  of neurotransmitters from the presynaptic neuron.
• step 2: Tiny sacs called synaptic vesicles release the neurotransmitters into the synapse
• step 3: These chemicals diffuse across the synaptic gap until they are picked up

  by receptors on the dendrite on the postsynaptic neuron.
• step 4: Each neurotransmitter will fit into a matching receptor site with a

  corresponding shape on the postsynaptic neuron.
• step 5: The neurotransmitter changes the chemical balance at the receptor site

  causing an action potential to fire along the next neuron.
• step 6: The neurotransmitters are then reabsorbed by the presynaptic

  neuron (reuptake) to be used again.