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AUTONOMIC NERVOUSSYSTEM
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Central nervous system (CNS) Peripheral nervous system (PNS)
Sensory (afferent)division
Motor (efferent) division
Somatic nervoussystem
Autonomic nervoussystem (ANS)
Sympatheticdivision
Parasympatheticdivision
Autonomic Nervous System (ANS)
Motor neurons that innervate smooth and cardiac muscle and glands.
Also called INVOLUNTARY NERVOUS SYSTEM.
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Figure 14.2 Comparison of motor neurons in the somatic and autonomic nervous systems.
Cell bodies in centralnervous system Peripheral nervous system
Neurotransmitterat effector
Effectororgans Effect
S O M A
T I C
N E R V O U S
S Y S T
E M
A U T O N O M I C N E R V O U S S Y S T E M
S Y M P A T H E T I C
P A R A S Y M P A T H
E T I C
Single neuron from CNS to effector organs
Heavily myelinated axon
ACh
Skeletal muscleStimulatory
Two-neuron chain from CNS to effector organs
Lightly myelinatedpreganglionic axons
Ganglion
Nonmyelinated
postganglionic axon
Epinephrine andnorepinephrine
ACh
ACh
Adrenal medulla Blood vessel
Lightly myelinatedpreganglionic axon
Ganglion
ACh
Nonmyelinatedpostganglionicaxon
ACh Smooth muscle(e.g., in gut), glands,cardiac muscle
Stimulatoryor inhibitory,dependingon neuro-transmitterand receptorson effector
organs
Acetylcholine (ACh) Norepinephrine (NE)
NE
+
+
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Somatic Nervous System vs.Autonomic Nervous System
Somatic NS Autonomic NS
Effectors
Neurons to effectors
Neurotransmitter(effects)
Ganglia ?
Skeletal Muscle Cardiac muscleSmooth muscleGlands
1 2: preganglionic neuron postganglionic neuron
Acetylcholine (stimulatory) Preganglionic: Ach
Postganglionic: Ach or NE (stimulatory or inhibitory)
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Central nervous system (CNS) Peripheral nervous system (PNS)
Sensory (afferent)division
Motor (efferent) division
Somatic nervoussystem
Autonomic nervoussystem (ANS)
Sympatheticdivision
Parasympatheticdivision
Dual innervation Visceral organs served by both divisions, but causeopposite effects
Autonomic Nervous System Divisions
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Dual Innervation
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Friday Night Scenario
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Role of the Parasympathetic Division
Promotes maintenance activities andconserves body energy Directs digestion, defecation Blood pressure, heart rate, and respiratory
rates are low Gastrointestinal tract activity high Pupils constricted Lenses accommodated for close vision
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Role of the Sympathetic Division
Exercise, excitement, emergency,embarrassment
Increased heart rate
Dry mouth Cold, sweaty skin Dilated pupils
Fight or flight system
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Role of the Sympathetic Division
During vigorous physical activityConstricts visceral blood vessels -> shunts blood to skeletal muscles and heartDilates bronchioles -> increases ventilation
Causes liver to release glucose
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Parasympathetic Sympathetic
Eye Eye
Salivaryglands
Brain stem
Cranial
Sympatheticganglia
Salivaryglands
Heart Cervical
Lungs
T1
Lungs
Heart
StomachThoracic
PancreasStomach
PancreasLiverand gall-bladderL1
Liver andgall-bladder
LumbarAdrenalgland
Bladder Bladder
Genitals Sacral Genitals
Skin*
Figure 14.3 The subdivisions of the ANS.
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Sympathetic NS Parasympathetic NS
Summary
Site of Origin
Fiber length
Ganglia location
Fight or Flight Rest and Digest
CNS:
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CN III Ciliaryganglion
Eye
Lacrimalgland
Pterygopalatineganglion
Nasalmucosa
Submandibularganglion
Submandibularand sublingualglands
Otic ganglionParotid gland
Heart
Cardiac andpulmonaryplexuses
Lung
Celiacplexus
Liver andgallbladder
Stomach
Pancreas
Largeintestine
Smallintestine
Rectum
Pelvicsplanchnicnerves
Inferiorhypogastricplexus
Urinarybladderand ureters
Genitalia (penis, clitoris, and vagina)
Preganglionic
PostganglionicCN Cranial nerveS Sacral nerve
CN VII
CN IXCN X
S 2
S 4
Figure 14.4 Parasympathetic division of the ANS.
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Cranial Part of Parasympathetic Division
Cell bodies in brain stem Preganglionic fibers in III,
VII, IX supply PSinnervation to head
supplies 90% of preganglionic PS fibersSupplies thoracic and abdominal viscera
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Sacral Part of Parasympathetic DivisionServes pelvic organs and distal half of large intestine
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Sympathetic (Thoracolumbar) Division
Preganglionicneurons arise inspinal cord segmentsT1 L 2
Preganglionic fiberssynapse close tospinal cord:
- in sympathetic trunk gagnlion or -collateral ganglion
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Adrenal medulla cells secrete NE and E are considered equivalent to postganglionic sympathetic neurons.
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18
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Stimulus
Receptor in viscera
Visceral sensoryneuron
Integration center May be preganglionic
neuron (as shown)
May be a dorsal horninterneuron
May be within wallsof gastrointestinaltract
Motor neuron
(two-neuron chain) Preganglionic neuron Postganglionic neuron
Visceral effector
1
2
4
5
3
Response
Dorsal root ganglion
Spinal cord
Autonomic ganglion
Figure 14.7 Visceral reflexes.
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Cholinergic Receptors
Two types of receptors bind Ach:
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Nicotinic Receptors
Found on Sarcolemma of skeletal muscle cell Sympathetic and parasympathetic
postganglionic neurons Cells of the adrenal medulla
Effect of ACh at nicotinic receptors
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Nicotinic Receptors
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Muscarinic Receptors
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Adrenergic Receptors
Bind NE Two major classes
Effects of NE (& E)
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Adrenergic Receptors
Eff f ANS di i i
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Effects of ANS divisions:
Heart (rate)
Organ Sympathetic Parasymp.
Most bloodvessels
Heart
blood vessels
Eff t f ANS di i i
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Effects of ANS divisions:
Eye
Organ Sympathetic Parasymp.
Adipose
Glands (nasal,lacrimal, gastricpancreas)
Eff t f ANS di i i
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Effects of ANS divisions:
Respiratory
Organ Sympathetic Parasymp.
Digestivesystem
Urinary system
S h i T
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Sympathetic Tone
Sympathetic tone (vasomotor tone)
Sympathetic division controls bloodpressure
P h i T
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Parasympathetic Tone
Parasympathetic division normally dominates:
The sympathetic division can override theseeffects during times of stress
L li d V Diff Eff
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Localized Versus Diffuse Effects
Parasympathetic division: short-lived,highly localized control over effectors
Sympathetic division: longer-lasting,bodywide effects
Communication atLevels of ANS control
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Communication atsubconscious level
Cerebral cortex(frontal lobe)
Limbic system(emotional input)
Hypothalamus The boss
: Overallintegration of ANS
Brain stem(reticular formation, etc.)
Regulates pupil size, heart,blood pressure, airflow,
salivation, etc.
Spinal cord Reflexes for urination,defecation, erection,
and ejaculation
Figure 14.8 Levels of ANS control .
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