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Autonomic Nervous System - Anatomy & Physiology

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  • What are the two main divisions of the autonomic nervous system (ANS)?
    Parasympathetic division and Sympathetic division.
  • What is the primary function of the parasympathetic division?
    Promotes maintenance and conserves body energy, often called the "rest and digest" system.
  • What is the primary function of the sympathetic division?
    Mobilizes the body for activity, often called the "fight or flight" system.
  • What is dual innervation in the ANS?
    Both parasympathetic and sympathetic divisions serve the same tissues but produce opposite effects.
  • Where are parasympathetic postganglionic cell bodies located?
    In terminal ganglia near or within the effector organs.
  • Which cranial nerves supply parasympathetic fibers to the head?
    Cranial nerves III, VII, and IX.
  • What additional tissues does the sympathetic division innervate that the parasympathetic does not?
    Sweat glands, arrector pili muscles in hair follicles, and smooth muscles of arteries and veins.
  • Where are sympathetic preganglionic neuron cell bodies located?
    In the lateral horns of the spinal cord gray matter.
  • What is the role of the adrenal medulla in the sympathetic nervous system?
    It acts as a modified sympathetic ganglion that secretes epinephrine and norepinephrine into the blood.
  • What neurotransmitter is released by all ANS preganglionic fibers?
    Acetylcholine (ACh).
  • Which fibers release norepinephrine (NE) in the ANS?
    Most sympathetic postganglionic fibers.
  • How do parasympathetic and sympathetic effects differ in duration and localization?
    Parasympathetic effects are short-lived and highly localized; sympathetic effects are diffuse and long-lasting.
  • What is sympathetic (vasomotor) tone?
    Continuous partial constriction of blood vessels maintained by sympathetic activity.
  • What is parasympathetic tone?
    Parasympathetic dominance that maintains heart rate and smooth muscle activity in digestive and urinary tracts.
  • What brain region is the integrative center for autonomic control?
    The hypothalamus.
  • Which part of the hypothalamus directs parasympathetic activity?
    The anterior hypothalamus.
  • Which part of the hypothalamus directs sympathetic activity?
    The posterior hypothalamus.
  • What is a visceral reflex arc?
    A reflex involving visceral sensory neurons that monitor chemical changes, stretch, temperature, or irritation.
  • Name a disorder caused by overactive sympathetic vasoconstriction.
    Hypertension (high blood pressure).
  • What is autonomic dysreflexia?
    Uncontrolled activation of autonomic neurons causing dangerous spikes in blood pressure, often in spinal cord injury patients.