Synaptic Transmission

• What is a synapse?


  The junction between a neurone and another neurone , or between a neurone and an effector cell
• What is the synaptic cleft?


  the tiny gap between the cells at a synapse
• what does the presynaptic neurone have?


  a swelling called a synaptic knob.
• What does a synaptic knob contain?


  This contains synaptic vesicles filled with neurotransmitters
• What is the presynaptic neurone?


  The neurone before the synapse
• What happens when an action potential reaches the end of a neurone?


  It causes neurotransmitters to be released into the synaptic cleft. They diffuse across to the postsynaptic membrane and bind to specific receptors
• what is the postsynaptic membrane?

  the membrane after the synapse
• What happens when neurotransmitters bind to receptors?

  they might trigger an action potential (in a neurone), cause muscle contraction (in muscle cell), or cause a hormone to be secreted from a gland cell
• Why are impulses unidirectional?


  Because the receptors are only on the postsynaptic membranes, synapses make sure impulses are unidirectiona
• Why are neurotransmitters removed from the cleft?


  So the response does not keep happening (eg they are taken back into the presynaptic neurone or broken down by enzymes)
• name some neurotransmitters?


  noradrenaline

  ACh
• What is ACh ?


  acetylcholine
• What are cholinergic synapses?

  Synapses that use acetylcholine