Synapse

• What are the features of synapses?

  • Unidirectionality
  • Summation
• What is spatial summation?


  A number of different pre-synaptic neurones release enough neurotransmitter to exceed the threshold value of the pre-synaptic neurone
• What is temporal summation?


  A single pre-synaptic neurone releases enough neurotransmitter many times over a short period of time to trigger an action potential
• What do inhibitory synapses do?

  Make it less likely for an action potential to be fired
• What is the process of inhibitory neurotransmission?

  • The pre-synaptic neurone releases a type of neurotransmitter that binds to chloride ion protein channels on the post-synaptic neurone
  • Chloride ion channel proteins open
  • Chloride ions move in via facilitated diffusion
  • This causes the opening of potassium ion protein channels
  • Potassium ions move out of the post-synaptic neurone into the synapse
• Which ions diffuse into the pre-synaptic neurone?

  Calcium ions
• What ions enter the post-synaptic knob to cause an action potential?

  Sodium ions