8/5/2011. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 1 Development of Complex Curricula for Molecular Bionics and Infobionics Programs within a consortial* framework** Consortium leader PETER PAZMANY CATHOLIC UNIVERSITY Consortium members SEMMELWEIS UNIVERSITY, DIALOG CAMPUS PUBLISHER The Project has been realised with the support of the European Union and has been co-financed by the European Social Fund *** **Molekuláris bionika és Infobionika Szakok tananyagának komplex fejlesztése konzorciumi keretben ***A projekt az Európai Unió támogatásával, az Európai Szociális Alap társfinanszírozásával valósul meg. PETER PAZMANY CATHOLIC UNIVERSITY SEMMELWEIS UNIVERSITY sote_logo.jpg dk_fejlec.gif INFOBLOKK 8/5/2011. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 2 Peter Pazmany Catholic University Faculty of Information Technology BASICS OF NEUROBIOLOGY STRETCH REFLEX www.itk.ppke.hu Neurobiológia alapjai (Nyújtási reflex) ZSOLT LIPOSITS Basics of Neurobiology: Stretch reflex 8/5/2011. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 3 www.itk.ppke.hu FEATURES OF REFLEXES THE REFLEX IS A RAPID, INVOLUNTARY NEURONAL REGULATORY ACTION EXECUTED IN RESPONSE TO SENSORY STIMULI IT IS ASSOCIATED WITH NEURONAL ASSEMBLIES OF SPINAL SEGMENTS ANDCRANIAL NERVE NUCLEI IT ENSURES THE ADAPTATION OF THE BODY TO EXTERNAL AND INTERNAL ENVIRONMENTS AND THE CONTINUOUSLY CHANGING CHALLENGES REFLEXES ARE USED IN THE REGULATION OF BOTH SOMATIC AND VISCERALFUNCTIONS SOME REFLEXES ARE INNATE, OTHERS ARE LEARNED ONES THE REFLEX MECHANISM STRUCTURALLY IS ORGANIZED IN THE REFLEX ARC THE EXAMINATION OF THE DIFFERENT REFLEXES GIVES PLENTY OF INFORMATION TO THE PHYSICIAN ABOUT THE OPERATION OF THE SENSORY, SOMATO-MOTOR AND VISCERO-MOTOR SYSTEMS Basics of Neurobiology: Stretch reflex 8/5/2011. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 4 www.itk.ppke.hu THE REFLEX ARC REFLEXES ARE EXECUTED VIA REFLEX ARCS EACH REFLEX ARC HAS FIVE MAIN STRUCTURAL CONSTITUENTS: 1. RECEPTOR. IT PICKS UP THE INFORMATION FROM THE INTERNAL AND EXTERNAL ENVIRONMENTS IN FORMS OF PHYSICAL AND CHEMICAL STIMULI 2. AFFERENTS. THESE ARE SENSORY NERVES THAT ARE LINKED WITH THE RECEPTORS AND CARRY THE STIMULUS-EVOKED INFORMATION TO THE PROCESSING CENTER. IN CASE OF SPINAL REFLEXES, NEURONS OF THE DORSAL ROOT GANGLIA SERVE THE ROLE OF AFFERENTS BY THEIR PROCESSES INTERCONNECTING THE RECEPTORS WITH THE GREY MATTER OF THE SPINALCORD 3. CENTER. PART OF THE SPINAL CORD OR BRAINSTEM THAT HANDLES, PROCESSES THE INCOMING SENSORY INFORMATION 4. EFFERENTS. SOMATOMOTOR OR VISCEROMOTOR NERVES THAT CONVEY THE GENERATED ADAPTIVE RESPONSE TO THE SITE OF THE COMPENSATORY ACTION 5. EFFECTOR. THESE UNITS EXECUTE THE REGULATORY COMMANDS Basics of Neurobiology: Stretch reflex 8/5/2011. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 5 www.itk.ppke.hu 1. RECEPTOR STRUCTURE2. AFFERENT NERVE FIBER 3. CNS CENTER 4. EFFERENT NER VE FIBER5. EFFECTOR STRUCTURE SCHEMATIC ILLUSTRATION OF THE REFLEX ARC 1. 2. 3. 4. 5. Basics of Neurobiology: Stretch reflex 8/5/2011. 6 www.itk.ppke.hu THE STRETCH REFLEX MUSCLE LENGTH AND MUSCLE TONE ARE IMPORTANT FEATURES OF MUSCLE FUNCTION AND THEIR REGULATION IS A KEY FACTOR IN MOVEMENTS THEY ARE CONTROLLED BY THE STRETCH REFLEX SYNONYMS FOR STRETCH REFLEX ARE MYOTATIC REFLEX OR PROPRIOCEPTIVE REFLEX IT IS A MONOSYNAPTIC, POSTURAL REFLEX THAT AMONG OTHERS WORKS AGAINST THE GRAVITY FORCE CHARACTERISTICS OF THE REFLEX INCLUDE: 1. STIMULUS: STRETCHING OF THE MUSCLE 2. RECEPTOR: MUSCLE SPINDLE, INTRAFUSAL MUSCLE FIBERS, NUCLEAR BAG AND NUCLEAR CHAIN RECEPTORS 3. AFFERENT PATH: IaAND II TYPE NERVE FIBERS OF SENSORY GANGLION CELLS 4. CENTER. SPINAL CORD, VENTRAL HORN, SOMATOMOTOR NEURONS (ALPHATYPE) 5. EFFERENT PATH: AXONS OF ALPHA MOTONEURONS 6. EFFECTOR STRUCTURE: EXTRAFUSAL MUSCLE FIBERS OF THE MUSCLE 7. COMPENSATORY ACTION: SHORTENING OF THE MUSCLE Basics of Neurobiology: Stretch reflex 8/5/2011. 7 www.itk.ppke.hu THE RECEPTOR STRUCTURE OF THE STRETCH REFLEX INNERVATION OF THE MUSCLE SPINDLE, THE RECEPTOR STRUCTURE OF THEMYOTATIC REFLEX. STATIC AND DYNAMIC RESPONSES GAMMA MOTONEURON NERVE FIBERS SENSORY TYPE Ia NERVE FIBERS SENSORY TYPE II NERVE FIBERS NUCLEAR BAG MUSCLE FIBER NUCLEAR CHAIN MUSCLE FIBER Basics of Neurobiology: Stretch reflex 8/5/2011. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 8 www.itk.ppke.hu THE KNEE JERK REFLEX A SHARP TAPON THE TENDON OF THE EXTENSOR MUSCLE STRETCHES IT,EVOKINGTHUSTHE ACTIVATION OF THE MUSCLE SPINDLE. THIS INFORMATION IS RELAYED VIA A MONOSYNAPTIC CONNECTION TO ALPHA MOTONEURONS IN THE SPINAL CORD. THE EFFERENT FIBERS FORCE THE EXTENSOR FOR CONTRACTION. THE REFLEX MAINTAINS THE PROPER CONSTANT LENGTH OF THE MUSCLE . . EXTENSOR MUSCLE FLEXOR MUSCLE TENDON Basics of Neurobiology: Stretch reflex 8/5/2011. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 9 www.itk.ppke.hu INHIBITION OF THE ANTAGONIST MUSCLES AS A RESULT OF THE KNEE JERK REFLEX, THE QUADRICEPS FEMORIS EXTENSOR MUSCLE UNDERGOES CONTRACTION. SIMULTANEOUSLY, THE DESCENDING AFFE-RENTSINHIBIT -VIA INTERNEURONS-THE ALPHA MOTONEURONS THAT SUPPLY THE ANTAGONIST FLEXOR MUSCULATURE L2-4 L5-S1-2 EXTENSOR MUSCLE FLEXOR MUSCLE Basics of Neurobiology: Stretch reflex 8/5/2011. TÁMOP –4.1.2-08/2/A/KMR-2009-0006 10 www.itk.ppke.hu THE GAMMA REFLEX LOOP THE ANTERIOR HORN IN ADDITION TO ALPHA MOTONEURONS ALSO CONTAINS SMALLER-SIZED CELLS, THE GAMMA MOTONEURONS GAMMA MOTONEURONS INNERVATE THE INTRAFUSAL MUSCLE FIBERS OF THE MUSCLE SPINDLE RECEPTOR DESCENDING TRACTS (CORTICOSPINAL, RUBROSPINAL, RETICULOSPINAL) EXCI-TE GAMMA MOTONEURONS CAUSING CONTRACTION OF THE INTRAFUSAL FIBERS AS A RESULT, THE INCREASED FIRING FROM SENSORY ENDINGS INFORMS THE ALPHA MOTONEURONS THAT WILL MAKE AN ADJUSTMENT OF THE MUS-CLE LENGTH . . DESCENDING TRACT GAMMA MOTONEURONS CAN ADJUST THE LEVEL OF SENSITIVITY OF MUSCLE SPINDLE RECEPTOR FIBERS, INITIATE CONTRACTION ACCORDING TO HIGHER MOTONEURON COMMANDS AND SET THE MUSCLE TONE