Organising the nervous system

• what are the different ways of organising the nervous system?

  • structural - CNS and PNS
  • functional - somatic and autonomic
• what is the PNS?

  • all neurons that connect CNS to rest of body
  • sensory neurons which carry nerve impulses from receptor to CNS, and motor which carry nerve impulses away from CNS to effector
• what is the autonomic NS?

  • system work constantly
  • under subconscious control and is used when body does something automatically - involuntary
  • e.g. heart beating
• what is the somatic NS?

  • system works under conscious control
  • used when you voluntarily decide to do something
  • e.g. decide to move a muscle in your arm
• what are the two types of nerve cells found in the CNS?

  • grey matter - unmyelinated
  • white matter - myelinated
• what is a ganglion?

  a collection of neuronal bodies found in the somatic and autonomic branches of the PNS

  • coordination centres for movement
• what does an antagonistic muscle mean?

  • a muscle that opposes the action of another
  • e.g. triceps oppose the contraction of the flexing of biceps by relaxing
• what occurs in the sympathetic nervous system?

  • active during flight/fight mode
  • ganglions located either side of spinal cord
  • shorter length of pre-ganglionic neurones
  • post-ganglionic neurotransmitter - noradrenaline
• what happens in the parasympathetic nervous system?

  • active during relaxation
  • ganglions located closer to target organ
  • longer length of pre-ganglionic neurone
  • post-ganglionic neurotransmitter is acetylcholine