neurons

• what is a neuron?

  a specialised cell that moves electrical impulses to and from the CNS
• what is a synapse?

  the point where one neuron can send chemical messages to an adjacent neuron
• what is a neurotransmitter?

  chemical messengers released by neurons
• what is a SSRI?


  drugs that influence process of neurotransmission
• what is action potential?

  electrical signal that travels down the neuron
• what are the 3 types of neurons?

  1. sensory
  2. relay
  3. motor
• what is a sensory neuron?

  carries nerve impulses from sensory receptors

  • receptors are found in eyes, ears and skin
  • helps deal with pain, heat and cold
• what is a relay neuron?

  allows sensory and motor neurons to communicate with each other

  • situated within the brain and spinal cord
• what is a motor neuron?

  directly and indirectly control muscles

  • releases neurotransmitters that bind to muscle fibres which triggers a response
• what's the rough size of a neuron?

  less than a millimetre to a metre long
• outline the function of the cell body

  holds the nucleus

  
• outline the function of the nucleus

  contains the genetic material of the cell
• outline the function of the dendrites

  branch-like structures

  • carry nerve impulses from neighbouring neurons towards cell body

  
• outline the function of the axons

  carries impulses away from the cell body down the length of the neuron

  
• outline the function of the myelin sheath

  fatty layer that covers the axon

  • protects axon
  • speeds up electrical transmission of impulse

  
• outline the function of the nodes of ranvier

  segments the myelin sheath

  • speed up transmission of impulse by forcing it to "jump" across the gaps in the axon

  
• outline the function of the terminal buttons

  found at the end of the axon

  • communicate with the next neuron across the synapse

  
• what are the 3 things the neurotransmitters do in synaptic transmission?

  1. excitation
  2. inhibition
  3. summation
• outline the role of excitatory neurotransmitters

  increase likelihood of new action forming in postsynaptic cell

  • depolarisation - positive electrical charge
• outline the role of inhibitory neurotransmitters

  decrease likelihood of new action forming in postsynaptic cell

  • hyperpolarisation - negative electrical charge
• what happens at summation of neurotransmitters?

  combined effect of excitatory and inhibitory on postsynaptic neuron

  • threshold is released, new action potential forms
• what is the process of synaptic transmission?

  1. action potential reaches axon terminal
  2. vesicles stimulate and release neurotransmitters
  3. neurotransmitters diffuse across synapse
  4. neurotransmitters bind with post-synaptic receptors
  5. summation occurs and next cell is inhibited or excited
  6. remaining neurotransmitters destroyed by enzymes or recycled in "reuptake"