Neurons and Synaptic Transmission

• Basic Neuron


  Label

  
• Sensory neurone

  • found in receptor cells e.g. eyes and skin
  • carry nerve impulses to CNS
  • not all reach the brain, some stop at spinal cord - reflex actions
  • dont connect to other neurones

  A) Myelin Sheath

  
• Motor Neurone

  • Efferent
  • commands from motor cortex in brain
  • controls movements
  • connect to skeletal muscle

  
• Relay Neuron

  • connects one neuron to another
  • network of cells in CNS which helps to produce info

  
• Example


  Sensory - hit a rock - to CNS

  Relay - in CNS

  Motor - Stops hitting rock
• Afferent


  brings information in e.g. sensory
• Efferent


  transfers info e.g. motor neuron
• Synaptic Transmission


  a way for one neuron to communicate with another
• Process of Synaptic Transmission

  1. Action potential travels along axon of presynaptic neuron
  2. Triggers vesicles to release neurotransmitters (a chemical message)
  3. NT diffuse across synaptic gap and bind to receptor sites on postsynaptic neuron
  4. NT either excite or inhibit
• Excitatory 


  e.g. noradrenaline

  post-synaptic neuron can fire action potential
• Inhibitory


  e.g. serotonin

  post-synaptic neuron may be unable to transmit signal
• Summation

  the total net of both inhibitory and excitatory potentials
• Sympathomedullary Pathway (SAM)


  short term response
• SAM pathway

  1. person enters stressful situation
  2. amygdala is activated and sends distress signal to hypothalamus
  3. hypo. activates SAM pathway - pathway that runs to the adrenal medulla and SNS
  4. SNS stimulates adrenal medulla
  5. secretes adrenaline and noradrenaline into blood
  6. Causes physiological changes