CH 15

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  1. chemical senses
    (smell & taste)
  2. Olfaction:
    • i. Uses chemoreceptors * found in olfactory epithelium consists of 3 cell types:
    • 1. supporting cells
    • 2. * ofactory cells (bipolar neurons w/ 6-8 cilia)
    • 3. basal cells (give rise to new supporting & olfactory cells)
  3. smells must
    • be volatile
    • be able to dissolve in mucus of epithelium
    • be able to cross membrane of olfactory cells & interact w/receptors
  4. 2 aspects to smell
    • 1.acuity – concentration perceived
    • 2.discrimination- number of scents distinguished
    • Threshold for smell- very low
    • Adaptation time- very rapid
  5. Gustatory
    • i.Uses chemoreceptors * located in taste buds; consist of 3 cell types:
    • 1.supporting cells
    • 2. gustatory cells- bipolar neurons w/ gustatory hair
    • 3.basal cells- give rise to the supporting & gustatory cells
  6. tastes must:
    • go into solution
    • enter taste porecross membrane & interact with receptors
  7. There are 5 basic tastes
    • a. Salty
    • b. Sweet
    • c. Sour
    • d. Bitter
    • e. Umani
  8. Light sense
  9. refraction
    bending of light rays as they travel through transparent media of differing densities (occurs 4X in our eyes)
  10. Myopia
    (correction- concave lens)
  11. Hyperopia
    (correction – convex lens)
  12. Astigmatism
    (correction- cylindrical lens)
  13. accommodation
    changing lens shape for near & far vision

    • distant: flatten lens, relax ciliary muscle
    • close: bulge lens, contract ciliary muscle
  14. presbyopia-
    old eyes, lack of ability to change lens shape as well
  15. constriction of pupils
    concentrate light on retina
  16. convergence of eyeballs
    both eyes directed to object being viewed
  17. chemical
    • conversion of light into an electrochemical impulse (nerve impulse) by stimulation of photoreceptors
    • involves a photopigment in the receptor changing shape when light hits it
  18. Rods
    contain rhodopsin,
  19. rhodopsin
    scotopsin (a protein) + retinal (vit A derivative)
  20. retinal bound to scotopsin (bent shaped)
    11- cis isomer
  21. all-trans isomer
    • struck by light it changes shape
    • shape change>chain of events>vision
  22. freed opsin sets of a chain reaction that hyperpolarizes photoreceptor
  23. bipolar neurons have two different types of receptors for the photoreceptors' neurotransmitters (turning them "off" and "on")
  24. the 2 diff responses of bipolar neurons also affect ganglion cells differently (excitation or inhibition)
  25. cones
    • -use the same basic process, but different photopigments (no rhopsodin)
    • - require brighter light to destabilize
    • - reform much more quickly
    • - 3 types red, green, blue
  26. rods
    up to 100 may converge on a single ganglion cell (providing fuzzy diffuse vision)
  27. cones vision
    each converges into its own ganglion cell (providing sharp detailed vision)
  28. movement senses
    hearing & equilibrium
  29. hearing
    concerned with the movement of sound waves
  30. sounds
    come from vibrations, we perceive their effects as sound
  31. pitch
    frequency of vibrations
  32. most sensitive
    1500-4000 hz
  33. hearing range
    20-20,000 cycles per second
  34. volume
    • amplitude of vibrations
    • measured in decibals
  35. damage to hair cells
    120 db
  36. review parts of ear and functions
  37. review structure of the cochlea
  38. route of sound waves through ear
  39. cochlea
    devoted to hearing
  40. 3 major parts of ear
    outter, middle, inner
  41. outter
    • pinna
    • external auditory canal
  42. function of outer ear
    • channel sound
    • pinpoint location
  43. middle ear
    • main function: amplification of sound/vibration
    • equalization of pressure
  44. middle ear structures
    • tympanic membrane
    • auditory ossicle: malleous, incus, stapes
    • oval window
  45. pharyngotympanic tube
    • eustachian tube
    • pressure needs to be equal on both sides
  46. static equilibrium
    • handled by structures in vestibule
    • saccule & utricle
    • perpendicular to one another
    • sense body orientation, esp head, relative to ground
  47. sensory cells static equilibrium
    • located in the macula
    • covered by the otolithic membrane
  48. dynamic
    • handled by semi circular canals
    • maintains body position, esp head, sudden movements
  49. dynamic sensory cells
    • located in cristae (w/in ampullae)
    • at base of semicircular canals,
    • coverd by cupula
Card Set
CH 15
Special senses
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