Transcript The Autonomic Nervous System

The Autonomic Nervous
System
Nervous System
Central
Peripheral
Somatic
Control out
Autonomic
Control inside
Def: Involuntary control of
the visceral organ activities
eg (circulation, digestion,
sweating, papillary size)
Division:
Sympathetic
Parasympathetic
Functional Anatomy
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The autonomic nerves consist of two neutrons.
1.
Preganglionic: Its cell body is located in the
2.
Postganglionic: Its cell body in a ganglion
CNS.
outside the CNS. It innervates the effector organ.
Single preganglionic neuron synapses with several
postganalionic neuronsspreading the effect over
a larger area.
Functional anatomy..cont
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Originate in the lateral
horn cells in the spinal
cord.
Sympathetic:
originate in the thoracic
and lumbar regions of
the spinal cord.
(Thoracolumbar)
Parasympathetic:
originate from cranial
nerves (3rd, 7th, 9th,
10th), and sacral spinal
nerves.
(craniosacral)
C3,7,9,10
P
T1-12
L2-3
S2-4
SYMP
P
Site of Ganglia
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Both systems are 2 neuron system.
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Sympathetic:
Preganglionic fibers are very
short, synapsing with cell
bodies of postganglionic
neurons within ganglia lie in
sympathetic ganglion chain
(sympathetic trunk).
Postganglionic fibers originate
in the ganglion chain terminate
on the effector organs.
Some preganglionic fibers pass
through the ganglion chain
without synapsing and
terminate later in sympathetic
collateral ganglia located
halfway between the CNS and
innervated organs.

C°
T1 о
T2 о
T3 о
effector
organ
Post
Pre
Site of ganglia
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Parasympathetic:
Ganglia are near or within the
effector organs.
Postganglionic fibers are shorter
than Preganglionic
Functions of the ANS
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The ANS controls involuntary visceral
organ activities.
Such as: circulation, digestion, sweating, and
papillary size.
The sympathetic and parasympathetic
systems exert opposite effects.
The sympathetic is activated during stress
& emergencies. Prepare for “fight or
flight”.
The parasympathetic is concerned with
vegetative functions (general
housekeeping), eg: feeding, resting and
sexual stimulation.
Sympathetic
Parasympathetic
ُُEye
Iris
Ciliary ms
Dilatation of pupil
Relaxation (far vision)
Lacrimal glands
non
Costriction of pupil
Contraction
(nearvision)
lacrimation
heart
Increase H.R
Increase force of cont
Dilatation of coronary bl
vessl
Vasoconstriction
Vasodilatation of sk ms
Decrease H.R
lungs
bronchodilation
constriction
GIT
Relax of walls &
Const of sphincters
(filling promoted)
Increase motility &secretion
Relaxation of sphincters
(emptying promoted)
Peripheral bl vessels
non
Sympathetic
Parasympathetic
Urinary bladder
Relax of walls &
Cont of internal sphincter
(filling promoted)
Cont of walls &
Relax of internal sphincter
(emptying promoted)
Sex organs
ejaculation
Erection of penis
Or clitoris
Chemical or neural transmitter
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All preganglionic fibers release acetylcholin (Ach).
All parasympathetic postganglionic release Ach.
All sympathetic postganglionic release
noradrenalin except sweat glands & bl vessels
to skeletal muscles.
Ach
Para
Ach
Symp
Noradrenalin (except sweat
Ach
glands & bl vessels to sk ms)
Chemical Division of ANS
 Cholinergic
 Adrenergic
(adrenalin&nor)
(Ach)
1.
2.
3.
All preganglionic most symp post
ganglionicnoradrenalin.
(para+symp)
Adrenalin
All Para Post
Adrenal medulla is a
ganglionic.
modified symp ganglion
Symp
that does not give rise to
postganglionic at
postganglionic fibers. It
sweat glands and secretes mainly adrenalin
blood vessels in
upon stimulation by
preganglionic.
skletal ms.
Ach
Adrenalin