Synaptic transmission

• Synapse


  Gap between neurons where the electrical impulse from the neuron is transmitted chemically
• Synapse


  • Synaptic vesicles connect to the membrane of the pre-synaptic neuron
  • Neurotransmitters are released into the synaptic cleft
  • Neurotransmitters diffuse across the synapse to connect with receptors on the post-synaptic neuron
• Action potential


  1. Electrical impulse causes synaptic vesicles in the axon (pre-synaptic neuron) to move down the axon

  2. Synaptic vesicles connect to the membrane of the pre-synaptic neuron

  3. Exocytosis releases neurotransmitters into the synaptic cleft

  4. Neurotransmitters diffuse across the synapse to connect with receptors on the post-synaptic neuron
• Neurotransmitters


  Chemicals that diffuse across the synapse to the next neuron in the chain
• Neurotransmitters


  • Each neurotransmitter has a specific molecular structure that fits perfectly into a post-synaptic receptor (lock and key)
  • Serotonin affects mood and social behaviour, which can be used to explain depression
• Excitation


  Receptor stimulation results in an increase in the positive charge of the post-synaptic neuron and increases the chance of the neuron firing and passing on the electrical impulse (Excitatory post-synaptic potential)
• Inhibition


  Receptor stimulation results in an increase in the negative charge of the post-synaptic neuron and decreases the chance of the neuron firing and passing on the electrical impulse (Inhibitory post-synaptic potential)
• Summation


  Addition of positive and negative post-synaptic potentials
• If inhibition then the post-synaptic neuron is less likely to fire, more likely to fire if excitatory
• There are three types of neurons: sensory, motor, and relay
• The presynaptic terminal contains synaptic vesicles that contain neurotransmitters.