PNS: Autonomic nervous system Autonomic NS regulates smooth muscle, cardiac muscle, gland tissue and adipocytes

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PNS Autonomic nervous system Autonomic NS
regulates smooth muscle, cardiac muscle, gland
tissue and adipocytes

• Anatomy of efferent pathways
• Sympathetic vs parasympathetic vs somatic motor
• Location of neurons and synapses
• Neurotransmitters
• Specific autonomic neuron functions
• Neurotransmitter receptor mechanisms

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Autonomic efferent neurons preganglionic and
postganglionic
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Neural Systems
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Parasympathetic Division

• Rest and digest, relaxed state
• Does not typically activate as a whole
• Decrease HR, increase digestive fxn
• Preganglionic neurons originate in midbrain,
  medulla, pons and 2-4 sacral
• Preganglionic fibers long, post short

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Sympathetic Division

• Fight or flight (prepares for intense activity)
• Heart rate increases, bronchioles dilate, plasma
  glucose increases
• Preganglionic neurons originate from spinal cord
  from T1 to L2 spinal nerves
• Preganglionic short, post-long
• Can have mass action distributed to heart, blood
  vessels, skin, adrenal glands

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http//medlib.med.utah.edu/kw/hyperbrain/anim/refl
ex.html
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Neurotransmitters and Receptors

• ACh receptor cholinergic receptors
• nicotinic
• muscarinic
• NE and E receptor adrenergic
• ?1 and ?2 (alpha)
• ?1 and ?2 (beta)

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Human Physiology, 6th ed., Fox, SI WC Brown,
Fig.9.9
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Parasympathetic

• preganglionic ACh nicotinic receptor
• is a Na / Kchannel
• postganglionic ACh muscarinic rec. G-protein
  coupled receptor links to 2nd messenger several
  different kinds

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Sympathetic

• preganglionic ACh nicotinic receptor is a
  Na / Kchannel
• postganglionic NE adrenergic receptor, alpha or
  beta, G-protein coupled receptor links to 2nd
  messenger
• (see Table 11.1)

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Adrenergic receptors
Rec. Intrac. effect Functional roles,
locations ?1 ? IP3,DAG contractile for smooth
m., blood vessels ?2 ? cAMP inhibitory, GI
tract, pancreas ?1 ? cAMP cardiac muscle,
kidney ?2 ? cAMP relaxes smooth m., GI tract,
blood vessels,bronchioles
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Autonomic Motor NS

• Central control by limbic system, hypothalamus,
  brainstem, spinal cord.
• Adrenergic receptors.
• Example pathways with autonomic motor efferents.

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Influence of Brain on Autonomic Functions

Thoughts emotions influence ANS by
hypothalamus.
ANS integrating center that interacts with
cerebrum, limbic system, brainstem, and spinal
cord.
ANS reflex centers for controlling pupil size,
accomodation, tear production, salivation,
coughing, digestive activities, heart, blood
vessel diameter and respiration.
ANS reflex control of defecation, urination,
genital erection and ejaculation.
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Spinal cord