GENERAL PRINCIPLES OF SENSORY TRANSDUCTION

04/22/23

GENERAL PRINCIPLES OF SENSORY TRANSDUCTION

Donald C. MikuleckyDepartment of PhysiologyandFaculty Mentoring Program

ORGANIZATION OF THE NERVOUS SYSTEM

BRAINSPINAL CORD

CENTRALNERVOUSSYSTEM (CNS)

PERIPHERALNERVOUS SYSTEM

AFFERENT

NERVES

EFFERENT

NERVES

EXTERO-RECEPTORS

INTERO-RECEPTORS

SOMATIC AUTONOMIC

EFFECTORORGANS

SKELETALMUSCLES

SMOOTH AND CARDIAC MUSCLES AND GLANDS

GENERAL PRINCIPLES OF SENSORY SYSTEMSSENSORY TRANSDUCTION: SPECIFIC

MODALITIES WITH ADEQUATE STIMULUSA SENSORY UNIT: SENSORY NEURON

AND ALL THAT IT INNERVATESEXTERORECEPTIVE AND

PROPRIORECEPTIVEPATHWAYSINTEGRATION

NEOCORTEX

THALAMUS

LIMBICCORTEX

BRAINSTEM

SPINALCORD

NOSE

EYE

TONGUE

EAR

SKIN

SMELL

VISION

TASTE

AUDITION

SOMATIC

SENSORY INFORMATION TRAVELSTO THE BRAIN VIA SPECIALIZED PATHWAYS

SENSORY MODALITIES AND RECEPTOR CELLS

MODE RECEPTOR ORGANVISION RODS,CONES EYEHEARING HAIR CELLS EARMOTION HAIR CELLS VESTIBULAR

APPARATUS

SMELL OLIFACTORYNEURONS

OLIFACTORYMUCOUS MEMB.

TASTE TASTE RECEPTORCELLS TASTE BUDS

TOUCH-PRESSURE

NERVE ENDINGS SKIN

SENSORY MODALITIES AND RECEPTOR CELLS

MODE RECEPTOR ORGANWARMTH NERVE ENDINGS SKINCOLD NERVE ENDINGS SKINPAIN NAKEDNERVE

ENDINGSSKIN

JOINTMOVEMENT &POSITION

NERVE ENDINGS VARIOUS

MUSCLELENGTH

NERVE ENDINGS MUSCLESPINDLE

MUSCLETENSION

NERVE ENDINGS GOLGI TENDONORGAN

TYPES OF ENERGY TRANSDUCED

RECEPTOR TYPE ENERGY HANDLEDMECHANORECEPTORSTOUCH,PRESSURE,PAIN

MECHANICAL: PRESSURE ORPHYSICAL DISPLACEMENT

THERMORECEPTORS HEAT OR COLDCHEMORECEPTORS:TASTE AND SMELL

CHEMICAL

PHOTORECEPTORS VISIBLE LIGHTNOCIOCEPTORS:PAIN

TISSUE DAMAGE

ADEQUATE STIMULUSA SPECIFIC STIMULUS UNIQUE TO A

SENSORY RECEPTOR

FOR EXAMPLE, PHOTORECEPTORS IN THE EYE RESPOND ONLY TO ELECTROMAGNETIC RADIATION

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

EXAMPLE: THE PACINIAN CORPUSCLEPRESSURE RECEPTORPRESSURE DISTORTS THE CAPSULE,

STRETCHING THE CELL MEMBRANESODIUM CHANNELS OPEN,

DEPOLARIZING THE MEMBRANEIF BEYOND THRESHOLD, ACTION

POTENTIAL RESULTS

SENSORY TRANSDUCTION

ADEQUATE STIMULUS

MEMBRANECONDUCTANCE

CHANGE

GENERATORPOTENTIAL

ACTIONPOTENTIAL

HOW IS THE INTENSITY OF THE STIMULUS ENCODED?

FREQUENCY CODING

POPULATION CODING

FREQUENCY CODINGLIGHT PRESSURE

LOW FREQUENCY

MORE PRESSURE

HIGHERFREQUENCY

POPULATION CODING

LIGHT PRESSURE

MORE PRESSURE

NEOCORTEX

THALAMUS

LIMBICCORTEX

BRAINSTEM

SPINALCORD

NOSE

EYE

TONGUE

EAR

SKIN

SMELL

VISION

TASTE

AUDITION

SOMATIC

THE LABELED LINE CODE OF STIMULUS QUALITY

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