Autonomic Nervous System

• Autonomic nervous system

  control organs, heart rate, homeostasis

  peripheral NS - carry instructions FROM CNS

  PARASYMPATHETIC/SYMPATHETIC
• somatic vs autonomic

  SOMATIC - single myelinated axon extending from CNS to effector (skeletal muscle)

  AUTOMATIC - two neurone chain:

  preganglionic - (first) neuron extends to ganglion

  postganglionic - (second) neuron extends from ganglion to effector organ
• Ganglia

  cell bodies of many peripheral autonomic neurones occur in clusters & form swellings on nerve trunks
• motor (efferent) pathway of ANS

  PREGANGLIONIC AUTONOMIC FIBRES - axons that form synapses with ganglion cells

  POSTGANGLIONIC AUTONOMIC FIBRES - axons innervating effector cells

  
• Neurotransmitters in ANS

  preganglionic nerves - ACh - cholinergic transmission

  postganglionic nerves - ACh - cholinergic

  and Noradrenaline - noradrenergic transmission

  PRE AND POST

  NON-ADRENERGIC NON-CHOLINERGIC TRANSMISSION - (NANC) - act as neurotransmitters - modulate action of main ntm

  
• parasympathetic NS

  cell bodies of preganglionic neurones in cranial and sacral regions of CNS

  sacral nerves - form synapses in ganglia located throughout pelvic region

  preganglionic nerves very long
• sympathetic NS

  cell bodies of preganglionic emerge to form synapse in:

  • chain of ganglia - paravertebral sympathetic chains - go up OR down chain
  • prevertebral ganglia - in abdomen
  • adrenal medulla - on top of kidneys form synapse with chromaffin cells