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SOMATIC SENSORY SYSTEMS AND PAIN

SOMATIC SENSORY SYSTEMS AND PAIN. D. C. MIKULECKY PROFESSOR OF PHYSIOLOGY AND FACULTY MENTORING PROGRAM. RECEPTIVE FIELDS. SIZE DETERMINES ACUITY LOCATION OF CELL BODY CORRESPONDS TO LOCATION AND SHAPE OF RECEPTIVE FIELD

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SOMATIC SENSORY SYSTEMS AND PAIN

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  1. SOMATIC SENSORY SYSTEMS AND PAIN D. C. MIKULECKY PROFESSOR OF PHYSIOLOGY AND FACULTY MENTORING PROGRAM

  2. RECEPTIVE FIELDS • SIZE DETERMINES ACUITY • LOCATION OF CELL BODY CORRESPONDS TO LOCATION AND SHAPE OF RECEPTIVE FIELD • THIS ORGANIZATION IS PRESERVED IN THE SOMATOTOPIC MAPS IN THE SOMATIC SENSORY CORTEX RECEPTIVE FIELDS TUTORIAL

  3. RECEPTIVE FIELDS BY CELL BODY LOCATION: DORSAL ROOT GANGLION + +

  4. RECEPTIVE FIELDS BY CELL BODY LOCATION: DORSAL ROOT GANGLION + +

  5. RECEPTIVE FIELDS BY CELL BODY LOCATION: DORSAL COLUMN NUCLEI HIGH OUTPUT INHIBITORY INTERNEURON

  6. RECEPTIVE FIELDS BY CELL BODY LOCATION: DORSAL COLUMN NUCLEI SMALL OUTPUT INHIBITORY INTERNEURON

  7. ANNULAR RECEPTIVE FIELDS - - DORSAL COLUMN NERVE CELLS +

  8. ANNULAR RECEPTIVE FIELDS - - - + -

  9. DIFFERENT TYPES OF RECEPTIVE FIELDS

  10. - - - - - - - - - + + + - - - OVERLAPPING ANNULAR RECEPTIVE FIELDS ARE RECTANGULAR

  11. SOMATOSENSORY CORTEX • SOMATOTOPIC ORGANIZATION • MORE AREA TAKEN BY SENSITIVE REGIONS (GREATER RECEPTOR DENSITY-SMALLER RECEPTIVE FIELDS) • CELLS RESPONDING TO ONE TYPE OF SENSATION IN VERTICLE COLUMNS(FOR EXAMPLE..PACINIAN CORPUSCLES IN A FINGERTIP)

  12. THE ANTEROLATERAL PAIN AND TEMPERATURE PATHWAY • SENSORY NEURONS SYNAPSE IN SUBSTANTIA GELATINOSA • SECONDARY NEURONS CROSS MIDLINE AND ASCEND IN ATEROLATERAL COLUMN • BRANCHES GO TO THE RETICULAR FORMATION • TERMINATE IN VENTROBASAL NUCLEUS OF THALMUS • TERTIARY NEURONS GO TO SENSORY CORTEX

  13. THE ANTEROLATERAL PATHWAY SUBSTANTIA GELITANOSA

  14. THE SENSATION OF PAIN • FAST PAIN • SLOW PAIN • MECHANICAL PAIN • CHEMICAL PAIN • THERMAL PAIN

  15. PAIN NERVES:

  16. FAST PAIN • OCCURS IN ABOUT 0.1 SECONDS • SUBJECTIVE DESCRIPTION:SHARP, ACUTE, ELECTRIC OR PRICKING • A FIBERS SYNAPSE ON CELLS IN LAMINA I (LAMINA MARGINALIS) IN THE DORSAL HORNS • SECONDARY NEURONS CROSS AND TRAVEL THROUGH THE ANTEROLATERAL PATHWAY TO THE VENTROBASAL COMPLEX OF THE THALAMUS • TERTIARY NEURONS GO TO THE PRIMARY SENSORY CORTEX

  17. FAST PAIN PATHWAY VENTROBASAL NUCLEUS LAMINA MARGINALIS I II IV III VI V VII SUBSTANTIA GELITANOSA ANTEROLATERAL PATHWAY IX VIII

  18. SLOW PAIN • OCCURS AFTER A SECOND OR MORE • OFTEN ASSOCIATED WITH TISSUE DESTRUCTION • SUBJECTIVELY DESCRIBED AS BURNING, ACHING,THROBBING, NAUSEOUS, OR CHRONIC • C FIBERS WHICH SYNAPSE IN THE SUBSTANTIA GELITANOSA • FINAL PROJECTION IS THE FRONTAL CORTEX

  19. SLOW PAIN PATHWAY VENTROBASAL NUCLEUS LAMINA MARGINALIS I II IV III VI V VII SUBSTANTIA GELITANOSA ANTEROLATERAL PATHWAY IX VIII

  20. MECHANICAL, CHEMICAL AND THERMAL PAIN • FAST PAIN IS GENERALLY MECHANICAL OR THERMAL • SLOW PAIN CAN BE ALL THREE • CHEMICAL PAIN RECEPTORS: BRADYKININ, SEROTONIN, HISTAMINE, POTASSIUM IONS, ACIDS, ACETYL CHOLINE AND PROTEOLYTIC ENZYMES • PROSTAGLANDINS ENHANCE PAIN SENSATION

  21. BRAIN STRUCTURES AND PAIN • COMPLETE REMOVAL OF THE SENSORY CORTEX DOES NOT DESTROY THE ABILITY TO PERCIEVE PAIN • STIMULATION OF THE SENSORY CORTEX EVOKES A SENSATION OF PAIN

  22. PAIN CONTROL (ANALGESIA) • THE ANALGESIA SYSTEM • THE BRAIN’S OPIATE SYSTEM • INHIBITION OF PAIN BY TACTILE STIMULATION • TREATMENT OF PAIN BY ELECTRICAL STIMULATION • REFERED PAIN

  23. THE ANALGESIA SYSTEM • PREAQUEDUCTAL GRAY • RAPHE MAGNUS NUCLEUS • PAIN INHIBITORY COMPLEX IN DORSAL HORNS

  24. PAIN INHIBITORY COMPLEX: PRESYNAPTIC INHIBITION BRAIN STEM.NEURON ANTEROLATERAL PATHWAY INHIBITORY NEURON - PAIN RECEPTOR + DORSAL HORN OF SPINAL CORD

  25. PAIN TRANSMISSION AND INHIBITION • SUBSTANCE P IS THE NEUROTRANSMITTER: BUILDS UP SLOWLY IN THE JUNCTION AND IS SLOWLY DESTROYED • PRESYNAPTIC INHIBITION BY INHIBITORY NEURON BLOCKS THE RELEASE OF SUBSTANCE P (ENKEPHALIN)

  26. THE BRAIN’S OPIATE SYSTEM • OPIATE RECEPTORS EXIST IN MANY CENTERS OF THE BRAIN, ESPECIALLY IN THE ANALGESIA SYSTEM • AMONG THE NATURAL SUBSTANCES WHICH ACTIVATE THESE RECEPTORS ARE: ENDORPHINS, ENKEPHALINS, AND MORPHINE

  27. INHIBITION OF PAIN BY TACTILE STIMULATION • STIMULATION OF LARGE SENSORY FIBERS FOR TACTILE SENSATION INHIBITS PAIN TRANSMISSION FOR SAME REGION • RUBBING OFTEN EASES PAIN • LINAMENTS, OIL OF CLOVE, ETC. • POSSIBLE EXPLANATION FOR ACUPUNCTURE?

  28. TREATMENT OF PAIN BY ELECTRICAL STIMULATION • STIMULATION OF LARGE SENSORY NERVES • ELECTRODES IN SKIN OR SPINAL IMPLANTS • INTRALAMINAR NUCLEUS OF THALAMUS

  29. REFERED PAIN • VISCERAL PAIN FIBERS SYNAPSE ON SAME SECONDARY NEURONS AS RECEIVE PAIN FIBERS FROM SKIN

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