Fisiologi Sistem Saraf OtonomDEPARTEMEN FISIOLOGI FK USUdr.Nuraiza Meutia,M.Biomeddr.Eka Roina Megawati,M.Kes

Tujuan Pembelajaran1.Menjelaskan fungsi dan divisi saraf otonom.2.Menjelaskan mekanisme kontrol saraf otonom.3. Menjelaskan karakteristik persarafan simpatis dan parasimpatis.4.Menjelaskan refleks otonom. *

The ANS consists of motor neurons that:

Innervate smooth and cardiac muscle, and glandsMake adjustments to ensure optimal support for body activitiesOperate via subconscious controlHave viscera as most of their effectors*

The two divisions of the ANS are the sympathetic and parasympathetic

The sympathetic mobilizes the body during extreme situationsThe parasympathetic performs maintenance activities and conserves body energy The two divisions counterbalance each others activity*

Parasympathetic activities

Decreased Heart RateDecreased Blood PressurePupil ConstrictionIncreased UrinationDecreased SweatingBronchial ConstrictionIncreased Salivation

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Sympathetic activities

Increased Heart RateIncreased Blood PressurePupil DilationDecreased UrinationIncreased SweatingBronchial DilationDecreased Salivation*

HOW IT HAPPENS ?*

Integration center of theAUTONOMIC NERVOUS SYSTEM is in the HIPOTALAMUSPONSMEDULLA*

Medullary, Pontine, and Mesencephalic Control of the Autonomic Nervous SystemMany neuronal areas in the brain stem, the medulla, pons, and mesencephalon, control different autonomic functions .Such asarterial pressure, heart rate,glandular secretion in the gastrointestinal tract, gastrointestinal peristalsis,and degree of contraction of the urinary bladder.etc

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Autonomic nerve pathwayExtends from CNS to an innervated organTwo-neuron chainPreganglionic fiber (synapses with cell body of second neuron)Postganglionic fiber (innervates effector organ)*

Anatomy of ANS*

DivisionOrigin of FibersLength of FibersLocation of GangliaSympatheticThoracolumbar region of the spinal cordShort preganglionic and long postganglionicClose to the spinal cordParasympatheticBrain and sacral spinal cordLong preganglionic and short postganglionicIn the visceral effector organs

Figure 14.3 ANATOMI

Sympathetic fibersalong with spinal nerves segment Toraco-Lumbal (T1 L3)

Parasympathetic fibers (cranio-sacral)along with cranial nerves - III, VII, IX, & X, and : spinal nerves S2, S3, dan S4*

Parasympathetic Division Outflow*

Cranial OutflowCranial NerveGanglionEffector Organ(s)Occulomotor (III)CiliaryEyeFacial (VII)Pterygopalatin SubmandibularSalivary, nasal, and lacrimal glandsGlossopharyngeal (IX)OticParotid salivary glandsVagus (X)Located within the walls of target organsHeart, lungs, and most visceral organsSacral OutflowS2-S4Located within the walls of the target organsLarge intestine, urinary bladder, ureters, and reproductive organs

Parasympathetic division : cranial & sacral outflow*

Sympathetic Outflow*

Sympathetic Trunks and PathwaysA preganglionic fiber follows one of three pathways upon entering the paravertebral ganglia1.Synapse with the ganglionic neuron within the same ganglion2.Ascend or descend the sympathetic chain to synapse in another chain ganglion3.Pass through the chain ganglion and emerge without synapsing*

Sympathetic Trunks and Pathways*Figure 14.6

Neurotransmitter in the ANS*Figure 14.2

Neurotransmitter in the ANS *The principal neurotransmitter in the ANS : Acetylcholine and NorepinephrineRecently acknowledge : ATP, NPY, VIP, Calcitonin gene-related peptide, & enkephalin

As in the sympathetic pathway :

Receptors in the ANS pathways :Cholinergic ReceptorMuscarinic (M1,M2,M3,M4,M5)...in the effector organsMuscarinic receptors are found on all effector cells that are stimulated by the postganglionic cholinergic neurons of either the parasympathetic nervous systemor the sympathetic system.*

Receptors in the ANS pathways :Cholinergic ReceptorNicotinic (N2)...in the gangliaNicotinic receptors are found in the autonomic ganglia at the synapses between the preganglionic and postganglionic neurons of both the sympathetic and parasympathetic systems. (Nicotinic receptors are also present at many nonautonomic nerve endingsfor instance, at the neuromuscular junctions in skeletal muscle

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Receptors in the ANS pathways :Adrenergic Receptor : in the effector organs1A, 1B, 1C2A, 2B, 2C1, 2, 3*

Sympathetic stimulation causes excitatory effects in some organs butinhibitory effects in others. Likewise, parasympathetic stimulation causes excitation in some but inhibition in others.

Responses of some effector organs to autonomic nerve activities*

Removal of the Ntransmitter at the postganglionic endingsAcetylcholine Catalyzed by Acetylcholinesterase acetate + choline.Reuptake choline into terminal nerve ending synthesis of new acetylcholine.

Norepinephrine, removed in 3 ways :1) reuptake into sympathetic nerve ending themselves (50-80 %)2) diffusion away into surrounding body fluid3) destruction by enzymes (small amounts) : MAO (in the nerve ending) or COMT (in all tissue)

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The differentiation between the two divisions :......fill in by yourself*Enhance your knowledge by studying this table in Ganongs (21-23rd Ed)

Characteristic Sympathetic Parasympathetic Origin fromPreganglionic fiberPostganglionic fiberNeurotransmitter PreganglionicPostganglionic

Termination of action

Autonomic ReflexesVisceral functions of the body are regulated by autonomic reflexes.

Examples :Cardiovascular Autonomic Reflexes. Baroreceptor reflex: BP stretch receptors (baro- receptors) in the walls of internal carotid arteries and the arch of the aorta signals transmitted to the brain stem inhibit the sympathetic impulses to the heart and blood vessels BP *

Pathway of Visceral Reflexes*

DISCUSS WITH FRIENDSGastrointestinal Autonomic Reflexes.

The smell of food / presence of food in the mouth initiates signals from the receptors in the nose and mouth the vagal, glossopharyngeal, and salivatory nuclei of the brain stem. transmit signals through the parasympathetic nerves the secretory glands of the mouth and stomach causing secretion of digestive juices (even before food enters the mouth)*

DISCUSS WITH FRIENDS Other Autonomic ReflexesEmptying of the urinary bladder : stretching of the bladder sends impulses to the sacral cord reflex contraction of the bladder and relaxation of the urinary sphincters.The sexual reflexes : psychic stimuli from the brain and the sexual organs result first in erection (mainly a parasympathetic function) and then ejaculation (partially a sympathetic function).The regulation of sweating, blood glucose concentration, ,etc.*

Alarm or Stress Response of theSympathetic Nervous SystemMental or physical stress can excite the sympathetic system, to provide extra activation of the body in states of stress the sympathetic stress response.

Large portions of the sympathetic nervous system discharge at the same time ( a mass discharge) :1. Increased arterial pressure2. Increased blood flow to active muscles concurrent with decreased blood flow to organs such as the gastrointestinal tract and the kidneys that are not needed for rapid motor activity*

3. Increased rates of cellular metabolism throughout the body4. Increased blood glucose concentration5. Increased glycolysis in the liver and in muscle6. Increased muscle strength7. Increased mental activity8. Increased rate of blood coagulation

The sum of these effects permits a person to perform far more strenuous physical activity . *

TERIMA KASIHREFERENSI :Frederic H. Martini. Fundamentals of Anatomy & Physiology.5th Ed. Prentice-Hall. 2001. pp :399-400, Elaine N.Marieb. Human Anatomy and Physiology. 6th Ed. Benjamin Cumming. 2004.Ganongs Review of Medical Physiology. 23rd Ed. McGraw Hill.2010.pp:261-271

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******************However, thepostganglionic sympathetic nerve fibers to the sweatglands, to the piloerector muscles of the hairs, and toa very few blood vessels are cholinergic.*****MAO : monoamine oxidaseCOMT : catechol-O-methyl transferase**********