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THE AUDITORY SYSTEM AND THE CHEMICAL SENSES D. C. MIKULECKY PROFESSOR OF PHYSIOLOGY AND FACULTY MENTORING PROGRAM.

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Presentation on theme: "THE AUDITORY SYSTEM AND THE CHEMICAL SENSES D. C. MIKULECKY PROFESSOR OF PHYSIOLOGY AND FACULTY MENTORING PROGRAM."— Presentation transcript:

1 THE AUDITORY SYSTEM AND THE CHEMICAL SENSES D. C. MIKULECKY PROFESSOR OF PHYSIOLOGY AND FACULTY MENTORING PROGRAM

2 THE NATURE OF SOUND zCOMPRESSION AND RARIFICATION OF AIR zWAVES OF HIGH AND LOW PRESSURE zTRANSMIT MECHANICAL FORCES

3 CHARACTERISTICS OF A PRESSURE WAVE A T = WAVELENGTH A = AMPLITUDE f = 1/T FREQUENCY

4 ANATOMY OF THE EAR zOUTER EAR zMIDDLE EAR zINNER EAR

5 OUTER EAR zACTS TO FOCUS SOUND WAVES ON THE TYMPANIC MEMBRANE zSHAPED LIKE A SOUND CONE

6 OUTER EAR PINNA CANAL

7 MIDDLE EAR zTHREE BONES LINK TYMPANIC MEMBRANE TO OVAL WINDOW zVIBRATIONS TRANSMITTED MECHANICALLY

8 MIDDLE EAR TYMPANIC MEMBRANE OVAL WINDOW BONES OF MIDDLE EAR COCHLEAR FLUID SOUND WAVE IN EAR CANAL

9 INNER EAR zSITE OF TRANSDUCTION zVIBRATION OF COCHLEAR FLUID CAUSES BASILAR MEMBRANE TO VIBRATE zHAIR CELLS ARE DEFORMED zAUDITORY NERVE BECOMES EXCITED AS HAIR CELLS DEPOLARIZE

10 INNER EAR OVAL WINDOW COCHLEA

11 STRUCTURE OF THE COCHLEA SCALA VESTIBULI COCHLEAR DUCT SCALA TYPANI OVAL WINDOW ROUND WINDOW

12 STRUCTURE OF COCHLEAR DUCT BASILAR MEMBRANE TECTORIAL MEMBRANE ORGAN OF CORTI

13 TRANSDUCTION MECHANISM BASILAR MEMBRANE…..VIBRATES TECTORIAL MEMBRANE STATIONARY STEROCILIA AUDITORY NERVE HAIR CELLS

14 TRANSDUCTION MECHANISM TECTORIAL MEMBRANE STATIONARY BASILAR MEMBRANE…..VIBRATES STEROCILIA BEND AUDITORY NERVE HAIR CELLS

15 FREQUENCY DISCRIMINATION: LOCALIZATION OF DISPLACEMENT OF BASILAR MEMBRANE BASE APEX HIGH LOW MID

16 AUDITORY PATHWAYS COCHLEA VENTRAL COCHLEAR NUCLEUS MIDLINE VENTRAL COCHLEAR NUCLEUS SUPERIOR OLIVE INFERIOR COLLICULUS

17 AUDITORY PATHWAYS (CONT.) MIDLINE SUPERIOR OLIVE INFERIOR COLLICULUS INFERIOR COLLICULUS MEDIAL GENICULATE MEDIAL GENICULATE TEMPORAL CORTEX TEMPORAL CORTEX

18 CHARACTERISTICS OF A PRESSURE WAVE A T = WAVELENGTH A = AMPLITUDE f = 1/T FREQUENCY

19 PROPERTIES OF AUDITORY NERVE CELLS zEACH AUDITORY NERVE FIBER HAS AN OPTIMUM FREQUENCY zTHIS TONOTOPIC ORGANIZATION ARISES FROM POSITION IN THE COCHLEA zTONIC AND PHASIC NEURONS IN EACH AREA zSOME RESPOND TO CHANGE IN FREQUENCY zSOME RESPOND TO CHANGE IN AMPLITUDE

20 SOUND LOCALIZATION zINTERAURAL TIME DIFFERENCE zTIME DELAY BETWEEN TWO EARS zALSO INTENSITY DIFFERENCES

21 DISORDERS OF AUDITION zLOSS OF HAIR CELLS: FREQUENCY SPECIFIC zTINNITUS: RINGING zCONDUCTIVE:l DAMAGE TO MIDDLE EAR zCENTRAL: BRAIN TUMORS AND LESIONS

22 TASTE SENSATION zGUSTATORY RECEPTORS zGUSTATORY PATHWAYS

23 GUSTATORY RECEPTORS zTASTE BUDS ON TONGUE LOCALIZED zSWEET: TIP zBITTER:BACK zSOUR SIDES zSALT: FRONT

24 GUSTATORY PATHWAYS zVII, IX, X CRANIAL NERVES zTO GUSTATORY NUCLEUS IN BRAIN STEM zVPM NUCLEUS OF THALAMUS zGUSTATORY AREA OF NEOCORTEX zVIA LIMBIC SYSTEM TO HYPOTHALAMUS

25 THE OLIFACTORY SYSTEM zRECEPTOR CELLS IN OLIFACTORY MUCOSAL MEMBRANE zAXONS CROSS CRIBIFORM PLATE AND TERMINATE ON MITRAL CELLS IN OLIFACTORY BULB-FORM OLIFACTORY TRACT zOLIFACTORY TRACT GOES TO LIMBIC SYSTEM AND TO ORBITOFRONTAL CORTEX zCLOSELY ASSOCIATED WITH EATING AND MATING BEHAVIOR


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