• ANS Anatomy
  • Autonomic and Somatic Innervation
  • Autonomic Reflex Arc
  • Autonomic Reflex Arc: First Link
  • Sensory Fiber Neurotransmitter(s)
  • Autonomic Nervous System Neurotransmitters: Summary
  • CNS and the Autonomic Nervous System
    • Spinal Cord Reflexes
    • Hypothalamus and Nucleus tractus solitarii
    • Higher Centers
  • Peripheral ANS Divisions
• Comparison between Sympathetic & Parasympathetic Systems
• Sympathetic Nervous System Anatomy
  • Diagram Sympathetic System
  • Anatomical Outline
    • Paravertebral Ganglia
    • Prevertebral Ganglia
    • Terminal Ganglia
    • Adrenal Medulla
• Parasympathetic System Anatomy
• ANS Neurotransmitter Effector Organs

• Interactions between Sympathetic & Parasympathetic Systems
• "Fight or Flight": Characteristics of the ANS

• ANS Neurotransmission
  • Neurotransmitter Criteria
  • Neurotransmission Steps:
    • Axonal Conduction
    • Storage and Release of Neurotransmitter
    • Combination of Neurotransmitter and Post-Junctional Receptors
    • Termination of Neurotransmitter Action
    • Other Non-electrogenic Functions
  • Cholinergic Neurotransmission
    • Transmitter Synthesis and Degradation
    • Acetylcholinesterase
    • Acetylcholine: Storage and Release
    • Site Differences:
      • Skeletal Muscle
      • Autonomic Effectors
      • Autonomic Ganglia
      • Blood vessels
    • Signal Transduction: Receptors
• Adrenergic Transmitters: Biosynthetic Pathways
• Adrenergic Neurotransmission: Introduction to the Neurotransmitters
• Catecholamine Synthesis, Storage, Release and Reuptake
  • Enzymes
  • Catecholamine storage
  • Regulation of adrenal medullary catecholamine levels
  • Reuptake
  • Metabolic Transformation
  • Indirect-acting sympathomimetics
  • Release
• Adrenergic Receptor Subtypes
  • ß-adrenergic receptors
  • Alpha-adrenergic receptors
  • Catecholamine Refractoriness
• Other Autonomic Neurotransmitters
  • Co-transmission
    • ATP
    • VIP
    • Neuropeptide Y family
  • Purines
  • Nitric Oxide (Modulator)
• Predominant Sympathetic/Parasympathetic Tone
• Baroreceptor Reflexes
• Pharmacological Modification of Autonomic Function
• Autonomic Dysfunction

• Cell bodies of preganglionic fibers: found in intermediolateral columns of the spinal cord (first thoracic to second or third lumbar segments
• Preganglionic fiber axons synapse with sympathetic ganglionic neurons which lie outside the cerebrospinal axis.
• Sympathetic ganglia are found at three sites:
  • Paravertebral
  • Prevertebral
  • Terminal

•  Paraverebral ganglia: 22 interconnected pairs on either sides of the vertebral column. (para: Gr: at the side or along side)
  • 
  • Myelinated preganglionic fibers (white rami: thoracolumbar outflow only) leave through the anterior spinal roots.
  • Postganglionic fibers (gray rami) runs back to spinal nerves for distribution to:
    • blood vessesls of the skin
    • blood vessels of skeletal muscle
    • sweat glands
    • pilomotor muscles

•   Prevertebral Ganglia: abdominal and pelvic location, comprised of:
  • celiac ganglia
  • superior mesenteric ganglia
  • aorticorenal and inferior mesenteric ganglia

•   Terminal Ganglia: few, residing near the innervated organ, including
  • ganglia associated with the urinary bladder and rectum
  • cervical ganglia (neck): three ganglia (chain) mediating vasomotor, secretory, pupillodilatory and pilomotor responses of the head and neck)
  • All postganglionic fibers arise from cell bodies located within these ganglia; the preganglionic fibers come from upper thoracic segments: No sympathetic preganglionic fibers come from above the first thoracic level

• Adrenal medulla is similar to sympathetic ganglia.
  • Difference:
    • Epinephrine is released (post-ganglionic sympathetic fibers release norepinephrine)
  • Chromaffin cells are innerved by preganglionic fibers that release acetylcholine.

Lefkowitz, R.J, Hoffman, B.B and Taylor, P. Neurotrasmission: The Autonomic and Somatic Motor Nervous Systems, In, Goodman and Gillman's The Pharmacologial Basis of Therapeutics, (Hardman, J.G, Limbird, L.E, Molinoff, P.B., Ruddon, R.W, and Gilman, A.G.,eds) TheMcGraw-Hill Companies, Inc.,1996, pp.105-107.

 

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Skeletal Muscle

Adrenergic Effects

Adrenergic Effects

• Usually, parasympathetic and sympathetic systems are physiological antagonists; that is, if one system facilitates or augments a process the other system inhibits the process.

• Since most visceral organs are innervated by both system, the activity of the organ is influenced by both, even though one system may be dominent.

• The general pattern of antagonism between sympathetic and parasympathetic systems is not always applicable. The interaction between sympathetic and parasympathetic systems may be independent or interdependent.

• Sympathetic system is most active when the body needs to react to changes in the internal or external environment: The requirement for sympathetic activity is most critical for:

• During rage or fright the sympathetic system can discharge as a unit--affecting multiorgan systems.

  • Sympathetic fibers show greater ramification.
  • Sympathetic preganglionic fibers may traverse through many ganglia before terminiating at its post-ganglionic cell. Synaptic terminal arborization results in a single preganglionic fiber terminating on many post-ganglionic cells.
  • This anatomical characteristic is the basis for the diffuse nature of sympathic response in the human and other species.

• Fight or Flight sympathetic reaction affects many systems:

• Parasympathetic system controls more discretely, reducing the level of resting organ function.

Lefkowitz, R.J, Hoffman, B.B and Taylor, P. Neurotrasmission: The Autonomic and Somatic Motor Nervous Systems, In, Goodman and Gillman's The Pharmacologial Basis of Therapeutics, (Hardman, J.G, Limbird, L.E, Molinoff, P.B., Ruddon, R.W, and Gilman, A.G.,eds) TheMcGraw-Hill Companies, Inc.,1996, pp.108..