The nervous system and the autonomic nervous system

• What is the primary function of the autonomic nervous system (ANS)?

  Regulation of visceral functions
• Why is the autonomic nervous system not under conscious control?

  It regulates involuntary bodily functions
• What are the divisions of the autonomic nervous system?

  • Sympathetic Division (SANS)
  • Parasympathetic Division (PANS)
  • Enteric Division

  
• What is the structure of the autonomic nervous system?

  It consists of a two neuron chain

  
• Where is the cell body of the first neuron in the autonomic nervous system located?

  In the central nervous system
• What is the first neuron in the autonomic nervous system called?

  Preganglionic Neuron
• What happens at the synapse in the autonomic nervous system?

  Second order neurons originate from ganglia
• Where do the preganglionic neurons of the sympathetic division lie?

  Between T1-L2
• What is the thoracolumbar outflow?

  Preganglionic neurons in the sympathetic division
• How many paired paravertebral ganglia are there?

  22 on either side of the spinal cord
• What can happen to preganglionic fibers in the sympathetic division?

  They may pass up/down the paravertebral ganglia
• What is an exception regarding some preganglionic neurons?

  They pass through ganglia without synapsing
• Where do some preganglionic neurons eventually synapse?

  In the prevertebral ganglia
• What do postganglionic neurons innervate?

  Glands, blood vessels, and smooth muscles
• How do some preganglionic fibers interact with the adrenal gland?

  They directly innervate the adrenal gland
• What is the effect of stimulating the adrenal gland?

  Release of adrenaline and noradrenaline
• What neurotransmitter is used between pre and postganglionic neurons in the SANS?

  Acetylcholine
• What receptor subtype is associated with acetylcholine in the SANS?

  Nicotinic
• What neurotransmitter is used between postganglionic neurons and effectors in the SANS?

  Noradrenaline
• Where do the cell bodies of preganglionic neurons in the PANS lie?

  In the brainstem and sacral spinal cord
• Where are the ganglia of the PANS located?

  Close to the effector structure
• What neurotransmitter is used between pre and postganglionic neurons in the PANS?

  Acetylcholine
• What receptor subtype is associated with acetylcholine in the PANS?

  Muscarinic
• What are the effects of the sympathetic and parasympathetic nervous systems?

  • Sympathetic: Increases heart rate, blood pressure
  • Parasympathetic: Decreases heart rate, promotes digestion

  
• How do visceral afferents enter the spinal cord?

  Via the dorsal horn
• Where do second order neurons terminate?

  In brainstem nuclei and thalamus
• What autonomic reflex is generated by activation of visceral afferents?

  Baroreceptor reflex
• What happens to normal reflex control in response to danger?

  It is overridden, increasing HR and BP
• What is the summary of the autonomic nervous system's functions?

  • Controls visceral homeostasis
  • Various subdivisions
  • Range of patterns of innervation and transmitters
  • Central control of ANS

  
• What is recommended for further reading on the autonomic nervous system?

  Pocock Chapter 11, pages 174-183