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GENERAL PRINCIPLES OF SENSORY TRANSDUCTION

GENERAL PRINCIPLES OF SENSORY TRANSDUCTION. Donald C. Mikulecky Department of Physiology and Faculty Mentoring Program. ORGANIZATION OF THE NERVOUS SYSTEM. BRAIN SPINAL CORD. CENTRAL NERVOUS SYSTEM (CNS). AFFERENT NERVES. EFFERENT NERVES. PERIPHERAL NERVOUS SYSTEM. EXTERO-

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GENERAL PRINCIPLES OF SENSORY TRANSDUCTION

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  1. GENERAL PRINCIPLES OF SENSORY TRANSDUCTION Donald C. Mikulecky Department of Physiology and Faculty Mentoring Program

  2. ORGANIZATION OF THE NERVOUS SYSTEM BRAIN SPINAL CORD CENTRAL NERVOUS SYSTEM (CNS) AFFERENT NERVES EFFERENT NERVES PERIPHERAL NERVOUS SYSTEM EXTERO- RECEPTORS INTERO- RECEPTORS SOMATIC AUTONOMIC EFFECTOR ORGANS SKELETAL MUSCLES SMOOTH AND CARDIAC MUSCLES AND GLANDS

  3. GENERAL PRINCIPLES OF SENSORY SYSTEMS • SENSORY TRANSDUCTION: SPECIFIC MODALITIES WITH ADEQUATE STIMULUS • A SENSORY UNIT: SENSORY NEURON AND ALL THAT IT INNERVATES • EXTERORECEPTIVE AND PROPRIORECEPTIVE • PATHWAYS • INTEGRATION

  4. SENSORY INFORMATION TRAVELS TO THE BRAIN VIA SPECIALIZED PATHWAYS NEOCORTEX LIMBIC CORTEX NOSE SMELL THALAMUS EYE VISION TASTE TONGUE BRAIN STEM EAR AUDITION SKIN SOMATIC SPINAL CORD

  5. SENSORY MODALITIES AND RECEPTOR CELLS

  6. SENSORY MODALITIES AND RECEPTOR CELLS

  7. TYPES OF ENERGY TRANSDUCED

  8. ADEQUATE STIMULUS • A SPECIFIC STIMULUS UNIQUE TO A SENSORY RECEPTOR • FOR EXAMPLE, PHOTORECEPTORS IN THE EYE RESPOND ONLY TO ELECTROMAGNETIC RADIATION

  9. GRADED VS ALL OR NONE • A RECEPTOR’S RESPONSE TO A STIMULUS IS GRADED • IF THRESHOLD IS EXCEEDED, THE ACTION POTENTIAL RESULTING IS ALL OR NONE

  10. EXAMPLE: THE PACINIAN CORPUSCLE • PRESSURE RECEPTOR • PRESSURE DISTORTS THE CAPSULE, STRETCHING THE CELL MEMBRANE • SODIUM CHANNELS OPEN, DEPOLARIZING THE MEMBRANE • IF BEYOND THRESHOLD, ACTION POTENTIAL RESULTS

  11. SENSORY TRANSDUCTION ADEQUATE STIMULUS MEMBRANE CONDUCTANCE CHANGE GENERATOR POTENTIAL ACTION POTENTIAL

  12. HOW IS THE INTENSITY OF THE STIMULUS ENCODED? • FREQUENCY CODING • POPULATION CODING

  13. FREQUENCY CODING LIGHT PRESSURE LOW FREQUENCY MORE PRESSURE HIGHER FREQUENCY

  14. POPULATION CODING LIGHT PRESSURE MORE PRESSURE

  15. THE LABELED LINE CODE OF STIMULUS QUALITY NEOCORTEX LIMBIC CORTEX NOSE SMELL THALAMUS EYE VISION TASTE TONGUE BRAIN STEM EAR AUDITION SKIN SOMATIC SPINAL CORD

  16. LOCALIZATION, DISTRIBUTION, AND ACUITY • CODING OF LOCATION DEPENDS ON RECEPTOR LOCATION • AREA COVERED BY RECEPTORS IN A SENSORY UNIT IS A RECEPTIVE FIELD • ACUITY DEPENDS ON THE DENSITY OF RECEPTORS

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