Home >Documents >Regulasi Sistem Saraf Otonom_

Regulasi Sistem Saraf Otonom_

Date post:05-Mar-2016
Category:
View:218 times
Download:0 times
Share this document with a friend
Transcript:
  • Regulasi Sistem Saraf OtonomYhusi Karina

  • Tujuan perkuliahanMahasiswa mampu menjelaskan:Struktur saraf otonomKontrol dan regulasi saraf otonomEfek saraf otonom terhadap berbagai organ terutama traktus urinariusAspek perkembangan saraf otonom

  • Development of autonomic nervous systemFrom the rostral/cranial end of the primitive streak, a long stiff structure develops in the mesoderm, elongating in the cranial direction. This becomes the notochord, which marks the head/tail axis of the embryo. ectodermal thickens to form the neural plate- closes neural tubeneural crest Dorsal root ganglia (autonomic nervous system)Migrate to form through the embryo: parasympathetic / sympathetic ganglia.Embryologically, adrenal medulla is derived from same cells as postganglionic ANS cells.

  • Organization of the Nervous SystemPeripheral Nervous SystemNerves and ganglia outside the central nervous systemNerve = bundle of neuron fibersNeuron fibers are bundled by connective tissue

  • The Autonomic Nervous SystemRegulate activity of smooth muscle, cardiac muscle & certain glandsStructures involvedgeneral visceral afferent neuronsgeneral visceral efferent neuronsintegration center within the brainReceives input from limbic system and other regions of the cerebrumGoverned by the hypothalamus that is located in the diencephalons

  • Nervous System

  • Autonomic versus Somatic NSAutonomic NS pathway is a 2 neuron pathway Somatic NS pathway only contains one neuron.

  • Basic Anatomy of ANSPreganglionic neuroncell body in brain or spinal cord axon is myelinated type B fiber that extends to autonomic ganglion

    Postganglionic neuroncell body lies outside the CNS in an autonomic ganglionaxon is unmyelinated type C fiber that terminates in a visceral effector

  • Divisions of the ANS2 major divisionsparasympatheticsympatheticDual innervationone speeds up organone slows down organSympathetic NS increases heart rateParasympathetic NS decreases heart rate

  • ANS NeurotransmittersClassified as either cholinergic or adrenergic neurons based upon the neurotransmitter released

    Adrenergic

    Cholinergic

  • ParasympatheticCholinergic neurons release acetylcholine from preganglionic neurons & from parasympathetic postganglionic neuronsAction: Excites or inhibits depending upon receptor type and organ involvedReceptor:Nicotinic receptors are found on dendrites & cell bodies of autonomic NS cells and at NMJ (all skeletal muscles, adrenal glands)Muscarinic receptors are found on plasma membranes of all parasympathetic effectors (receptors of some sweat glands)

  • AcetylcholineNicotinic receptorsNm (muscular-type or N2): skeletal muscleNn (neuron-type, or N1): autonomic ganglia, CNSMuscarinic receptorsPostganglionic parasympathetic and a few sympathetic sites, CNS (also autonomic gang.)Receptor subtypes: M1-5

  • CatecholamineNorepinephrinePostganglionic sympathetic, CNS, adrenal medullaReceptors: a1, a2, b1EpinephrineAdrenal medulla, CNSReceptors: a1, a2, b1 , b2DopamineAutonomic ganglia, CNSReceptors: D(1-5), a1, b1

  • SympatheticAdrenergic neurons release nor epinephrine (NE) from postganglionic sympathetic neurons onlyAction: Excites or inhibits organs depending on receptorsReceptor:Alpha1 and Beta1 receptors produce excitationAlpha2 and Beta2 receptors cause inhibitionBeta3 receptors (brown fat) increase thermo genesisNE lingers at the synapse until enzymatically inactivated by monoamine oxidase (MAO) or catechol-O-methyltransferase (COMT)

  • Comparison of Somatic and Autonomic Nervous SystemsCopyright 2003 Pearson Education, Inc. publishing as Benjamin Cummings

  • Autonomic Nervous System

  • The enteric nervous systemNerve plexuses within the wall of the digestive tract. Contributions from: sensory neurons between digestive tract and CNS,ANS motor neurons between the CNS and the digestive tract, enteric neurons confined within the plexusesFunctionsStimulate/inhibit smooth muscle contractionStimulate/inhibit gland secretionsDetect changes in content of lumenInterneurons connect sensory and motor aspects of enteric

  • Autonomic FunctioningSympathetic fight-or-flightResponse to unusual stimulusTakes over to increase activitiesRemember as the E division = exercise, excitement, emergency, and embarrassmentParasympathetic housekeeping activitiesConserves energyMaintains daily necessary body functionsRemember as the D division - digestion, defecation, and diuresis

  • Responses to Exercise (Fight or Flight Response)Alarm reaction = flight or fight response dilation of pupilsIncreased heart rate and force of contraction & BPincrease in blood flow (Blood vessel dilation) in skeletal and cardiac musclesDilation of air passageways & respiratory rate increasesEnergy sources availability increased (blood glucose level increase)Glycogen to glucoseFat cells break down triglyceridesMuscles generate heat, body temperature increasesSweat gland activity increasesDecrease in nonessential organ activities decrease in blood flow to nonessential organs

    Long lasting due to lingering of NE in synaptic gap and release of nor epinephrine by the adrenal gland

  • Parasympathetic ResponsesEnhance rest-and-digest activitiesMechanisms that help conserve and restore body energy during times of restNormally dominate over sympathetic impulsesSLUDD type responses = salivation, lacrimation, urination, digestion & defecation 3 decreases--- decreased HR, diameter of airways and diameter of pupilParadoxical fear when there is no escape route or no way to wincauses massive activation of parasympathetic divisionloss of control over urination and defecation

  • Autonomic or Visceral ReflexesAutonomic reflexes occur over autonomic reflex arcs. Components of that reflex arc:sensory receptorsensory neuronintegrating centerpre & postganglionic motor neuronsvisceral effectorsUnconscious sensations and responseschanges in blood pressure, digestive functions etcfilling & emptying of bladder or defecation

  • Autonomic ReflexesParasympathetic reflex via vagus lowers heart rate.

    Sympathetic reflex via cardiac accelerator nerves (sympathetic) cause heart rate to increase.

  • Regulation of ANSAutonomic reflexes control most of activity of visceral organs, glands, and blood vessels.Autonomic reflex activity influenced by hypothalamus and higher brain centers, but it is the hypothalamus that has overall control of the ANS.Sympathetic and parasympathetic divisions influence activities of enteric nervous system through autonomic reflexes. These involve the CNS. But, the enteric nervous system can function independently of CNS through local reflexes.

  • Enteric Nervous System: Autonomic and Local ReflexesRegulation of activity of digestive tractSensory neurons of enteric plexuses supply CNS with informationAutonomic neurons affect responses of smooth muscle and glandsLocal reflex: does not involve CNS. Produces involuntary, unconscious, stereotypical response to stimulus.

  • Influence of Brain on Autonomic Functions

  • Influence of Brain on Autonomic Functions

  • Control of Autonomic NSNot aware of autonomic responses because control center is in lower regions of the brainHypothalamus is major control centerHypothalamus regulates balance (tone) between sympathetic and parasympathetic activity levelsinput: emotions & visceral sensory information smell, taste, temperature, osmolarity of blood, etcoutput: to nuclei in brainstem and spinal cordposterior & lateral portions control sympathetic NSincrease heart rate, inhibition GI tract, increase temperatureanterior&medial portion control parasympathetic NSdecrease in heart rate, lower blood pressure, increased GI tract secretion and mobility

  • Autonomic DysreflexiaExaggerated response of sympathetic NS in cases of spinal cord injury above T6Certain sensory impulses trigger mass stimulation of sympathetic nerves below the injuryResultvasoconstriction which elevates blood pressureparasympathetic NS tries to compensate by slowing heart rate & dilating blood vessels above the injurypounding headaches, sweating warm skin above the injury and cool dry skin belowcan cause seizures, strokes & heart attack

  • HPA AxisHypothalamus-Pituitary-AdrenalChart by Franklyn SillsSlide prepared by John Chitty, Colorado School of Energy Studies, www.energyschool.com

    Sistem saraf termasuk yang berkembang paling awal selama embriyoNeuron pada sistem saraf berkembang dari tiga jaringan embrional utama, yaitu sel krista neural, plakoda ektoderm, dan neuroepitelium. Pada minggu ketiga perkembangan mudigah (setelah pembuahan), lapisan ektoderm akan berbentuk cakram datar, yang lebih luas di daerah kepala (kranial) daripada di daerah kaudal. Ektoderm yang terletak di atas notokord akan menebal dan membentuk lempeng saraf. Pelipatan naik tepi-tepi lateral lempeng saraf akan membentuk lipat-lipat saraf, sementara di daerah tengah akan terbentuk alur saraf. Secara perlahan lipat-lipat saraf akan saling mendekat ke garis tengah dan mengalami penyatuan. Penyatuan ini dimulai dari daerah bakal leher dan berjalan ke arah kepala dan kaudal. Hasil dari penyatuan ini disertai penutupan neurosprus di daerah kranial dan kaudal adalah tabung saraf.Pada saat pelipatan tepi-tepi lempeng saraf, sel-sel krista (yang berada di bagian ektoderm) akan terdesak dan bermigrasi dari ektoderm ke mesoderm di bawahnya dan membentuk sel krista neural (neural crest cell). Sel krista neural ini akan terbentang memanjang di antara ektoderm permukaan dan tabung saraf yang terbentuk. Kemudian sel krista neural akan bermigrasi ke arah lateral (samping) tabung saraf membentuk ganglia sens