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Def: Involuntary control of the visceral organ activities eg (circulation, digestion, sweating, papillary size)
Division: Sympathetic
Parasympathetic
Functional Anatomy
The autonomic nerves consist of two neutrons.
1. Preganglionic: Its cell body is located in the CNS.
2. Postganglionic: Its cell body in a ganglion outside the CNS. It innervates the effector organ.
Single preganglionic neuron synapses with several postganalionic neuronsspreading the effect over a larger area.
Functional anatomy..cont
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
P
SYMP
S2-4
T1-12L2-3
Site of Ganglia Both systems are 2 neuron system. 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 оT2 оT3 о effector organ
PrePost
Site of ganglia
Parasympathetic: Ganglia are near or within the
effector organs. Postganglionic fibers are
shorter than Preganglionic
Functions of the ANS 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.
EyeIrisCiliary ms
Lacrimal glands
heart
Peripheral bl vessels
GIT
Dilatation of pupilRelaxation (far vision)
non
VasoconstrictionVasodilatation of sk ms
Increase H.RIncrease force of contDilatation of coronary bl vessl
Relax of walls &Const of sphincters(filling promoted)
bronchodilationlungs
Costriction of pupilContraction (nearvision)lacrimation
non
Decrease H.R
Increase motility &secretionRelaxation of sphincters(emptying promoted)
constriction
Sympathetic Parasympathetic
Urinary bladder
Sex organs
Relax of walls &Cont of internal sphincter(filling promoted)
ejaculation
Cont of walls &Relax of internal sphincter(emptying promoted)
Erection of penisOr clitoris
Sympathetic Parasympathetic
Chemical or neural transmitter 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
AchPara
Noradrenalin (except sweat
glands & bl vessels to sk ms) Symp
Ach
Chemical Division of ANS Cholinergic
(Ach)
1. All preganglionic (para+symp)
2. All Para Post ganglionic.
3. Symp postganglionic at sweat glands and blood vessels in skletal ms.
Adrenergic (adrenalin&nor)
most symp post ganglionicnoradrenalin.
Adrenalin Adrenal medulla is a
modified symp ganglion that does not give rise to postganglionic fibers. It secretes mainly adrenalin upon stimulation by preganglionic.
AdrenalinAch