Synaptic Transmission

• Neurotransmitters

  • Chemical messengers of the nervous system
  • They get released from a synaptic vesicle into the synaptic gap
  • They affect the transfer of an impulse to another nerve or muscle
  • Any excess neurotransmitters are reabsorbed (taken back up) into the pre-synaptic neurons through the process of reuptake
  • Or they are broken down by an enzyme
•   Structures of Neurotransmitters

  
• Synaptic Transmission through the synaptic gap

  
• Excitation and Inhibition

  • Neurotransmitters can be excitatory or inhibitory
  • Excitatory - they make it more likely the next neuron will fire (such as adrenaline)(increase potential)
  • Inhibitory - they make it less likely the next neuron will fire (such as serotonin)(decrease potential)
• Action Potential

  • When a neuron ‘fires’ it produces an action potential
  • A short lasting event which occurs when a neuron sends information down an axon, away from the cell body
  • They are triggered by a process called summation
  • Summation is the process that determines the production of an action potential
  • The effects of excitatory and inhibitory signals combined need to reach the threshold voltage to trigger an action potential
  • Resting voltage of a membrane - 70 mv
  • The membrane needs to get to around - 55 mv for the next neuron to fire