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Sensory Physiology_hearing

Sensory Physiology_hearing. The Ear. Houses two senses Hearing Equilibrium (balance) Receptors are mechanoreceptors. Hearing: Mechanoreceptors. Sound waves Conduction Air Bone Fluid Membranes To hair cell. Anatomy of the Ear. The ear is divided into three areas

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Sensory Physiology_hearing

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  1. Sensory Physiology_hearing

  2. The Ear • Houses two senses • Hearing • Equilibrium (balance) • Receptors are mechanoreceptors

  3. Hearing: Mechanoreceptors • Sound waves • Conduction • Air • Bone • Fluid • Membranes • To hair cell

  4. Anatomy of the Ear • The ear is divided into three areas • Outer (external) ear • Middle ear • Inner ear Figure 8.12

  5. The External Ear • Involved in hearing only • Structures of the external ear • Pinna • External auditory canal Figure 8.12

  6. The External Auditory Canal • Narrow chamber in the temporal bone • Lined with skin • wax glands are present • Ends at the tympanic membrane

  7. The Middle Ear or Tympanic Cavity • Air-filled cavity within the temporal bone • Only involved in the sense of hearing

  8. The Middle Ear or Tympanic Cavity • Two tubes are associated with the inner ear • The opening from the auditory canal is covered by the tympanic membrane • The auditory tube connecting the middle ear with the throat • Allows for equalizing pressure during yawning or swallowing • This tube is otherwise collapsed

  9. Bones of the Tympanic Cavity • Three bones span the cavity • Malleus (hammer) • Incus (anvil) • Stapes (stirrip) Figure 8.12

  10. Bones of the Tympanic Cavity • Vibrations from eardrum move the malleus • These bones transfer sound to the inner ear Figure 8.12

  11. Inner Ear or Bony Labyrinth • Includes sense organs for hearing and balance • Filled with perilymph Figure 8.12

  12. Inner Ear or Bony Labyrinth • A maze of bony chambers within the temporal bone • Cochlea • Vestibule • Semicircular canals Figure 8.12

  13. Hearing: Mechanoreceptors Figure 10-19: Sound transmission through the ear

  14. Mechanisms of Hearing Figure 8.14 Slide 8.29

  15. Hearing: Hair Cell Transduction Figure 10-20: The cochlea

  16. Organs of Hearing • Organ of Corti • Located within the cochlea • Receptors = hair cells on the basilar membrane • Gel-like tectorial membrane is capable of bending hair cells • Cochlear nerve attached to hair cells transmits nerve impulses to auditory cortex on temporal lobe Slide 8.27a

  17. Organs of Hearing Figure 8.13 Slide 8.27b

  18. Mechanisms of Hearing • Vibrations from sound waves move tectorial membrane • Hair cells are bent by the membrane • An action potential starts in the cochlear nerve • Continued stimulation can lead to adaptation Slide 8.28

  19. Hearing: Hair Cell Transduction • Fluid wave moves • Tectoral membrane • Steriocilia move • Ion channels open • Depolarization • NT release • Sensory nerve AP

  20. Hearing: Hair Cell Transduction Figure 10-21: Signal transduction in hair cells

  21. Hearing: Integration and Problems • Pitch • Intensity • Localization • Integration • Thalamus • Auditory cortex • Deafness • Conductive • Sensory / neural Figure 10-5: Localization of sound

  22. Hearing: Integration and Problems Figure 10-22: Sensory coding for pitch

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