331 7.1 Physiology

  1. functions of the outer ear
    • sound collector - pinna
    • a resonator - the EAM
  2. cupping the ear adds
    3 - 6 dB
  3. functions of the middle ear
    • an impedance transformer
    • the acoustic reflex
  4. define impedance
    • resistance to the flow of energy
    • in the ear the change of mediums (air to fluid) results in around a 30dB loss of sound intensity
  5. three mechanisms of the middle ear impedance transformer
    • the catenary lever effect
    • the lever effect of the ossicular chain
    • the spike heel effect
  6. the spike heel effect has to deal with
    the tympanic membrane
  7. the acoustic reflex
    only the stapedius contracts in humans
  8. sensory transduction
    putting sound into neural code
  9. low frequency registers at the
    apex cochlea
  10. high frequecy registers at the
    base of cochlea
  11. draw the basilar membrane
    slide 13
  12. the scala media does what
    rocks back and forth
  13. frequency always goes
    in the ame direction (cannot be reversed)
  14. which part of the basilar membrane wears out first
    the base which is why you lose hearing high frequencies first
  15. at the peak of the traveling wave
    shearing takes place
  16. afferent innervation comes from
    the inner hair cell
  17. in many hearing losses
    only the outer hair cells are damaged
  18. endolymph has lots of
  19. perilymph has no
  20. paradox explained
    silent current from differences btw K+ in endolymph and perilymph
  21. cochlear amplifier
    the flow of fluid from movement of outer hair cells causes movement/shearing of inner hair cells
  22. hair cell cillia are
  23. inner hair cells have what above, across, and below
    • endolymph above
    • reticular lamina - hair cell fits into the reticular lamina
    • perilymph below
  24. outer hair cells are surrounded by
    space so that they can vibrate and produce sound
  25. outer hair cells are like
    joy sticks that only work in 2 directions
  26. normal hearing people hear
    soft --> loud
  27. old people hear
    from med. high --> loud
  28. K+ flows into
    te organ of corti and is pumped back into perilymph
  29. majority of deafness is caused when
    K+ does not move properly
  30. all cillia are
    bound / linked together and work together
  31. if sound is loud enough...
    you do not need outer hair cells
  32. kemp echo
    • 2nd beep back
    • 2nd beep is a reflection from hair cells
  33. the role of the inner ear amplifier
    • sound into round window --> outer hair cells sheared --> K+ flows into perilymph -->
    • K+ pumped back into endolymph --> fluid movement causes inner hair cells to shear allowing hearing below 60dB
  34. the outer hair cells are capable of
    changing length
  35. the place / traveling wave theory
    • helmholz bekesy
    • which nerve fires
  36. cochlear animation
    like a piano
  37. the frequency / volley theory
    • rutherford boring
    • how the nerve fires
    • if fired at a or b a thousand times, you hear a thousand hertz
  38. how many rows of outer and inner hair cells
    • outer - 3
    • inner - 1
  39. ringing of ears occurs when
    all three rows randomly fire
  40. if you destroy all but 1 row..
    you get constant feedback or constant ringing
  41. the ear canal amplifies sound between
    • 3,000 - 5,000 Hz
    • 20dB
Card Set
331 7.1 Physiology
auditory physiology