Download NERVOUS SYSTEM: AUTONOMIC NERVOUS SYSTEM

Human Anatomy Unit 4 NERVOUS SYSTEM: AUTONOMIC NERVOUS SYSTEM Func0onal Overview of the Nervous System The Autonomic Nervous System •  “Involuntary” •  Func0on to modulate ongoing automa0c ac0vi0es •  Effectors (target 0ssues) –  smooth muscle –  cardiac muscle –  glands •  Func0onal examples: –  heart rate –  ven0la0on –  diges0ve tract ac0vity ANS is a Two Neuron System •  Preganglionic fibers –  exit the CNS and terminate onto autonomic ganglia •  Postganglionic fibers –  exit the autonomic ganglia and terminate onto the target ANS is a Two Neuron System Components and Subdivisions of the ANS •  Sympathe0c division –  Fight or flight –  Preganglionic fibers emerge from T1‐L2 –  Postganglionic neurons emerge from sympathe0c chain ganglia •  Parasympathe0c division –  Rest and repose –  Preganglionic fibers emerge from pons, medulla, S2‐S4 –  Postganglionic neurons within effector Components and Subdivisions of the ANS Organiza0on of the Sympathe0c Division Sympathe0c Division •  Sympathe0c chain –  Loca0on: either side of vertebral column –  Innervate effectors in body wall, inside thoracic cavity –  preganglionic fibers synapse on postganglionic fibers very close to the CNS and far away from effector organs •  Collateral ganglia –  Loca0on: between sympathe0c chain and effector •  Adrenal medulla –  Sympathe0c preganglionic neurons enter adrenal medulla and s0mulate postganglionic neurons –  Cells respond and release adrenalin (80% epinephrine, 20% norepinephrine) Anatomical Distribu0on of Sympathe0c Postganglionic Fibers Collateral Ganglia •  Celiac ganglion –  Stomach, duodenum, liver, pancreas, spleen, gallbladder •  Superior mesenteric ganglion –  Small intes0nes, beginning of large intes0nes •  Inferior mesenteric ganglion –  Kidney, bladder, reproduc0ve organs, large intes0nes Adrenal Medulla Organiza0on of the Parasympathe0c Division Parasympathe0c Division •  Involves cranial nerves: III, VII, IX and X, S2‐S4 •  Innervates visceral organs •  Preganglionic fibers synapse on postganglionic fibers far away from the CNS and within effector organs Anatomical Distribu0on of Parasympathe0c Postganglionic Fibers Dual Innerva0on Levels of Autonomic Control