neuronal communication

• define stimulus

  • changes in the external or internal environment
• outline ways in which sensory and motor neurones are similar

  • both have a cell body , axon and dendrites
  • axons carry impulse away from cell body
  • are myelinated with Schwann cells
  • cell bodies have lots of mitochondria and RER to produce neurotransmitters
  • have Na - K+ pumps and bolted gated ion channels
• what is the cell body of neurone for ?

  • to produce neurotransmitters
• how does the Pacinian corpuscle act as a transducer

  • is a mechanoreceptor which converts change in pressure into electrical impulse
  • pressure in the skin changes shape of the stretch mediated Na+ channel to open
  • Na+ depolarise cell creating a generator potential
  • generator potential creates an action potential
  • action potential is transmitted along neurone
• describe the importance of synapses between neurones

  • ensures impulse is unidirectional
  • spatial summation : different presynaptic neurones release neurotransmitter at the same time generating an action potential
  • temporal summation : the same neurone releasing neurotransmitter over a period of time to generate an action potential
• outline ways in which the structure of sensory and motor neurone differ

  • cell body of MN is in CNS
  • MN has no dendron
  • SN has cell body in the middle
• how does a synapse make sure transmission is unidirectional

  • only the presynaptic neurone has Ca2+ channels and acetylcholine vesicles
  • neurotransmitter receptors are only on the postsynaptic neurone
• define refractory period 


  the short period of time after an action potential where the axon cannot be depolarised again
• how would a toxin of similar shape to the neurotransmitter prevent the initiation of an action potential

  • competes with neurotransmitters to bind to receptor
  • Na+ channels remain closed
  • postsynaptic membrane does not depolarise
  • generator potential not established
  • threshold value not reached
• what is GABA's mode of action

  • inhibitory neurotransmitter
  • causes hyperpolarisation in the post synaptic neurone
• at very high temperatures why does conduction of an impulse stop

  • ion channels denature
  • acetylcholinesterase denatures
• define generator potenial


  impulse produced by a sensory receptor following transduction