The Autonomic Nervous System (ANS)Chapter 17

Autonomic Nervous System (ANS)Motor regulation of smooth muscle, cardiac muscle, glands & adipose tissue (visceral effectors) through stimulation of visceral efferent fibers Sympathetic () division fight or flight response Parasympathetic (P) division rest & repose (conserve & restore) responsedual innervation if organ receives both & P, one division excites, the other inhibits activity

Overview of ANS anatomySomatic efferent:CNSSomatic motor neuronSkeletal muscle

Sympathetic cell bodies of preganglionic neurons in lateral gray horns of spinal cord T1-L2 (thoracolumbar division) axons of pregg neurons exit with spinal nerves into white ramus (part of rami communicantes) to travel to: sympathetic chain ganglion, or collateral (prevertebral) ganglion,& adrenal medulla pregg fibers release Ach postgg neurons usually release norepinephrine (NE) effects on visceral effectors usually excitatory but depend upon specific receptor present ( or )

Sympathetic:Preganglionic neuronPostganglionic neuronVisceral effector(myelinated, cholinergic)(excitatory synapse)unmyelinatedEffect may be excitatory or inhibitory depending on receptorsLateral gray horns T1-L2 Chain ganglionPrevertebral ganglionAlpha() or beta ()

Parasympathetic cell bodies of preganglionic neurons found in cranial nerve nuclei (III, VII, IX, X) & lateral gray horns S2-S4 (craniosacral division) pregg P neurons travel to terminal ganglion (close to) or intramural ganglion (within wall) of effector both pre & postganglionic P fibers release Ach effects on organ depend on specific receptor present (nicotinic or muscarinic)

Parasympathetic:Preganglionic neuronPostganglionic neuronVisceral effector(myelinated, cholinergic)(excitatory synapse)unmyelinatedEffect may be excitatory or inhibitory depending on receptorsCNs (III, VII, IX, X) & Lateral gray horns S2-S4 Terminal ganglionIntramural ganglionNicotinic or Muscarinic

Autonomic Nervous SystemMental activityPupilsLacrimal glandsSalivary glands

Sweat glandsBronchiolesHeartCoronary arteriolesBlood glucose/lipidsStomach motilityAdrenal glandsKidney outputGastrointestinal glandsIntestinal motilityAbdominal arteriolesBladder toneAnal/urethral sphinctersGenitals

Skin blood vesselsSkeletal muscleSympathetic, adrenergic(thoracolumbar)Parasympathetic, cholinergic(craniosacral)IncreasesDilated

Decreases production

Increases productionDilatedIncreases rateDilatedIncreasesDecreasesIncreases productionDecreasesDecreases productionDecreasesConstrictedDecreases (relaxes muscle)Increased toneEjaculation

ConstrictedVessels dilated/increases energy production and use

-----ConstrictedTear productionIncreases production

-----ConstrictedDecreases rate----------Increases-----IncreasesIncreases productionIncreases----- (dilated)IncreasesRelaxesErection

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Activities of the ANSEffects of Sympathetic Activation -fight or flight response (energy expenditure): increased cardiovascular & respiratory activity increased blood flow to brain (increased alertness), skeletal muscles, heart muscle, lungs increased visual acuity (pupil dilation) release of energy reserves from adipose, liver, & skeletal muscles decrease in non-essential functions (ie. digestion) release of Epi & NE from adrenal medullae to continue effects

Activities of the ANSEffects of Parasympathetic Activation -rest & repose response (conserve & restore energy): decreased cardiovascular & respiratory activityincreased GI motility & enzyme secretionpupil constriction nutrient uptake & energy storage into adipose, liver, & skeletal muscles (glycogen)

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