Autonomic Autonomic Nervous System

Dr. Sama-ul-Haque

ObjectivesObjectives Define autonomic nervous system.

Describe sympathetic and parasympathetic nervous system.

Enumerate the functions of sympathetic and parasympathetic nervous system.

ANS is the subdivision of the peripheral nervous ANS is the subdivision of the peripheral nervous system that regulates body activities that are generally system that regulates body activities that are generally not under conscious controlnot under conscious control

Visceral motorVisceral motor innervates innervates non-skeletalnon-skeletal ( (non-somatic) non-somatic) musclesmuscles

Composed of a special group of neurons serving: Composed of a special group of neurons serving: Cardiac muscle (the heart)Cardiac muscle (the heart) Smooth muscle (walls of viscera and blood vessels)Smooth muscle (walls of viscera and blood vessels) Internal organsInternal organs SkinSkin

The Autonomic Nervous System

Basic anatomical difference between the motor Basic anatomical difference between the motor pathways of the voluntary somatic nervous system (to pathways of the voluntary somatic nervous system (to skeletal muscles) and those of the autonomic nervous skeletal muscles) and those of the autonomic nervous systemsystem

Somatic division:Somatic division: Cell bodies of motor neurons reside in CNS (brain or spinal Cell bodies of motor neurons reside in CNS (brain or spinal

cord)cord) Their axons (as nerves) extend all the way to their skeletal Their axons (as nerves) extend all the way to their skeletal

muscles.muscles.

Autonomic system: chains of two motor neuronsAutonomic system: chains of two motor neurons 11stst = preganglionic neuron (in brain or cord) = preganglionic neuron (in brain or cord) 22ndnd = gangionic neuron (cell body in ganglion outside CNS) = gangionic neuron (cell body in ganglion outside CNS)

Axon of 1Axon of 1stst ( (preganglionicpreganglionic) neuron leaves ) neuron leaves CNS to synapse with the 2CNS to synapse with the 2ndnd ( (ganglionicganglionic) ) neuron.neuron.

Axon of 2Axon of 2ndnd ( (ganglionicganglionic) neuron extends to the ) neuron extends to the organ it servesorgan it serves

Diagram contrasts somatic (lower) and autonomic:

autonomic

somatic

this dorsal root ganglion is sensory

Divisions of the autonomic nervous systemDivisions of the autonomic nervous system

Parasympathetic divisionParasympathetic division Sympathetic divisionSympathetic division

Serve most of the same organs but cause Serve most of the same organs but cause opposing or antagonistic effectsopposing or antagonistic effects

Parasympathetic: routine maintenance“rest &digest”

Sympathetic: mobilization & increased metabolism “fight, flight or fright”

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Where they come fromWhere they come from

ParasympatheticCraniosacral

SympatheticThoracolumbar

T1 to L2

Paravertebral Paravertebral Ganglionic Ganglionic

chainchain or or

Sympathetic Sympathetic TrunkTrunk

Paravertebral Ganglionic

chain

Spinal NerveSpinal Nerve

Sympathetic nerveSympathetic nerve

Sympathetic Nervous system

Parasympathetic Nervous system

Functions of Sympathetic Nervous System Functions of Sympathetic Nervous System Increased Heart RateIncreased Heart Rate Increased Blood PressureIncreased Blood Pressure Pupil DilationPupil Dilation Decreased UrinationDecreased Urination Increased SweatingIncreased Sweating Bronchial DilationBronchial Dilation Decreased SalivationDecreased Salivation

Functions of Parasympathetic Nervous Functions of Parasympathetic Nervous System System

Decreased Heart RateDecreased Heart Rate Decreased Blood PressureDecreased Blood Pressure Pupil ConstrictionPupil Constriction Increased UrinationIncreased Urination Decreased SweatingDecreased Sweating Bronchial ConstrictionBronchial Constriction Increased SalivationIncreased Salivation

Thank You