SYNAPTIC TRANSMISSON

• Steps of synaptic transmission:

  • Nerve impulse arrives at synaptic knob, causing depolarisation of the presynaptic membrane
  • Voltage-gated calcium ion (Ca2+) channel proteins open
  • Calcium ions diffuse into the synaptic knob and cause synaptic vesicles to fuse with the presynaptic membrane
  • Acetylcholine is released and diffuses across the synaptic cleft
  • Acetylcholine binds to its receptors on the postsynaptic membrane
  • This leads to the opening of sodium ion channels in the postsynaptic membrane
  • Sodium ions diffuse into the postsynaptic neurone
• • Depolarisation of the postsynaptic membrane occurs
  • If threshold potential is reached, an action potential will be generated and a nerve impulse will be sent along the postsynaptic neurone