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بسم الله الرحمن الرحیم

1390 1Isfahan Medical Faculty, Biomedical Sciences Department

Autonomic Nervous System

Autonomic Nervous System

Dr . Ebrahim Esfandiary

14/02/90

Dr . Ebrahim Esfandiary

14/02/90


1390 Isfahan Medical Faculty, Biomedical Sciences Department

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5Figure 12.2b

Autonomic System

Sympathetic divisionParasympathetic division


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Sympathetic division

• Descending autonomic pathway

• Sympathetic center in spinal cord

• Sympathetic chain

• Sympathetic fibers

• Adrenal medulla


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Parasympathetic division

• Descending autonomic pathway

• Dorsal nucleus of vagus

• Sacral parasympathetic center

• Vagus nerve

• Pelvic splanchnic fibers


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پارا و سمپاتيك اعصاب زيع تومختلف ساختمانهاي در سمپاتيك

بدنپاراسمپاتيك و سمپاتيك بخش دو به خودكار عصبي سيستم

ميشود .تقسيم . در ميشود توزيع بدن تمام در سيستم اين سمپاتيكي بخش

مغزي حاليكه اعصاب طريق از پاراسمپاتيكي و 9، 7، 3بخشميشوند 10 توزيع لگني اسپالنكنيك اعصاب و .

دارند بدن در محدودتري توزيع پاراسمپاتيك اعصاب بنابراينندارند پاراسمپاتيك عصب سوماتيك بافتهاي ديگر عبارت به

عصب خودكار عصبي سيستم بخش هردو از احشاء بيشترمیکننددريافت

فقط بافتها براي بعضی مي كنند دريافت عصب بخش يك ازپاراسمپاتيكي مثال رشته فقط اشكي میکنددريافت غده

مي كنند دريافت سمپاتيكي رشته فقط جنسي و آدرنال غدد


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Hitch hiking journey

• Autonomic system hitch hike through whole body along:

1- the somatic ( or visceral) nerves

2- Relevant arteries


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Sympathetic Post ganglionic fibers distribute in one of the following 5 pathways:


Depart of A.S.B.S


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Somatic Sympathetic ParasympatheticNerves Division Division

UMN

LMN


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CNS P N S


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PRE-GANGLIONICPRE-GANGLIONIC


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GANGLIAGANGLIA


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POST-GANGLIONICPOST-GANGLIONIC


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Depart of A.S.B.S


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Autonomic Efferent: Basic Principles• Somatic efferent path has just 1 neuron• Autonomic efferent path has 2 neurons:

– Preganglionic and postganglionic

• Sympathetic system is in the thoracolumbar region• Parasympathetic is cranio-sacral in location


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Sympathetic System General Features:

• Long postganglionic fibers • Pre Gan N / Post Gan N = Very small ratio or high

divergence = 1/5

1390 Isfahan Medical Faculty, Biomedical Sciences Department 34

Parasympathetic System: General Features

• Pre Gan N / Post Gan N = small ratio or low divergence += 1/2

• More localized effects


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General functions of Parasympathetic system

• Protecting, resting and compensating bodily organs:– decreased heart rate– salivation and digestion– bowel and bladder emptying– papillary constriction


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PARASYMPATHETIC SUMMARY ACTIONS

• short-term control– ACh is quickly destroyed

• gastrointestinal tone

• paradoxical fear reaction– Paradoxical fear reaction occurs when there is no escape route

or no way to win• massive activation of the Parasympathetic

system• loss of control over urination or defecation


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Sympathetic System Neurons

• The site of cell body of preganglionic neurons :– Intermediolateral

column T1 – L2

• The site of cell body of postganglionic neurons:– paravertebral ganglia

in sympathetic chain– prevertebral ganglia

near origins of celiac and mesenteric arteries


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Parasympathetic Preganglionic Neurons

• The sites of cell body of Cranial Preganglionic neurons

• They are found in 4 locations– Edinger-Westphal-III– Sup salivatory nuc-VII– Inf salivatory nuc-IX– Dorsal nuc vagus &– Uppermost part of nuclus

ambiguus-X

• The sites of cell body of Pelvic Preganglionic neurons :

• S2, S3, S4– Project to terminal

ganglia in colon, rectum, bladder, prostate & vaginal glands, & erectile tissue of the penis and clitoris


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Parasympathetic Postganglionic Neurons

• The sites of cell body of Cranial Postganglionic neurons:– Ciliary ganglion-III– Pterygopalatine &

Submandibular gang-VII

– Otic gang-IX– The wall of thoracic,

abdominal viscerae

• The sites of cell body of Pelvic Postganglionic neurons:– The wall of pelvic

viscerae


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Heart Force , Rate @


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intermediolateral Column T12-L2I

Uterus (Contraction )*


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Comprehensive table of Autonomic system

• Digestive system

• Heart

• lung

• Kidney

• Eye

• Genital


Sciences Department

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THE ENDTHE END


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Sympathetic Parasympathetic Division DivisionUMN

LMN

SomaticNerve


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Receptors of the ANSNamed after the nerve type that innervates them

Cholinergic Receptors:

The receptors on which Ach acts

NicotinicNM

NN

MuscarinicM1 – 15

Adrenergic Receptors:

The receptors on which NEP and EP act

αα1

α2

ßß1

ß2

DD1D2


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Cholinergic RECEPTORS …

1. Nicotinic :Nicotine• The toxin obtained from tobacco

leaves which activates these receptors and always has a stimulatory action

2. Muscarinic– Muscarine

• The poison from a mushroom which activates these receptors at the effector site


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Cholinergic RECEPTORS …

Kinds of nicotinic cholinoreceptors : ACh receptors on the adrenal

medulla ACh receptors on the

postganglionic neuron at the synapse between pre- and postganglionic neurons

ACh receptors on skeletal muscle

Muscarinic cholinoreceptor can be stimulatory or inhibitory


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ADRENERGIC RECEPTORS

alpha-1 – excitation (most common alpha)

alpha-2 – inhibition

beta-1 -- excitation beta-2 – inhibition (most common beta)

SYMPATHETIC NERVOUS SYSTEM

• Prepares body to deal with stress– Fight or flight response

• Neurotransmitters are epinephrine and norepinephrine– Chemical substances that facilitate

excitation or inhibition of target cells


• A drug that stimulates the sympathetic nervous system is known as a sympathomimetic or adrenergic agent

• A drug that inhibits the sympathetic nervous system is called a sympatholytic or anti-adrenergic agent

• Ex. Propanolol ( beta blocker )


PARASYMPATHETIC NERVOUS SYSTEM

• Controls vegetative functions– Constriction of pupils, slowing of heart rate,

constriction of bronchioles, etc.• Neurotransmitter is Acetylcholine• A drug that stimulates the system is called a

Parasympathomimetic or cholinergic drug– Eg. Prostigmine

• A drug that blocks or inhibits the system is called a Parasympatholytic or anticholinergic drug– Eg. Atropine


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