SYNAPTIC TRANSMISSION

• Schwann cells make up the myelin sheath of myelinated neurons. The gaps are nodes of ranvier
• synapse is a junction between a neuron and the next cell
• the gap between the cells is a synaptic cleft
• • presynaptic knob contains vesicles full of NTS
  • when electrical impulses reach the knob the vesicles move to the pre synaptic membrane and release the NTS
  • NTS diffuse across cleft and bind to receptors on post synaptic membrane triggering responses such as an electrical impulse or hormone secretion if the post synaptic cell is a gland
• impulses are undirectional cos receptors are only on the post synaptic membrane
• NTS left in cleft are reuptaken by pre synaptic neuron or broken down by enzymes
• NTS can be excitatory ( increase likelihood of electrical impulses being triggered) or inhibitory ( make it less likely)
• NTS

  • acetylcholine = movement, memory, learning, sleep
  • dopamine = pleasure and reward
  • noradrenaline = similar to adrenaline
  • serotonin = mood reg
  • GABA = inhibits impulses
• summation = total charge inside neruon
• action potential = impulse, if reaches threshold of -55mv the neuron fires
• saltatory conduction = impulse jumps between nodes of ranvier to increase charge - makes firing more likely