Special senses pt 1

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Special senses pt 1

  1. 1. Special Senses Part One <br />Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings<br />
  2. 2. The Senses<br /><ul><li>General senses of touch
  3. 3. Temperature
  4. 4. Pressure
  5. 5. Pain
  6. 6. Special senses
  7. 7. Smell
  8. 8. Taste
  9. 9. Sight
  10. 10. Hearing
  11. 11. Equilibrium</li></ul>Slide 8.1<br />Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings<br />
  12. 12. The Eye and Vision<br /><ul><li>70 percent of all sensory receptors are in the eyes
  13. 13. Each eye has over a million nerve fibers
  14. 14. Protection for the eye
  15. 15. Most of the eye is enclosed in a bony orbit
  16. 16. A cushion of fat surrounds most of the eye</li></ul>Slide 8.2<br />Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings<br />
  17. 17. Accessory Structures of the Eye<br /><ul><li>Eyelids
  18. 18. Eyelashes</li></ul>Figure 8.1b<br />Slide 8.3a<br />Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings<br />
  19. 19. Accessory Structures of the Eye<br /><ul><li>Meibomian glands – modified sebacious glands produce an oily secretion to lubricate the eye</li></ul>Figure 8.1b<br />Slide 8.3b<br />Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings<br />
  20. 20. Accessory Structures of the Eye<br /><ul><li>Ciliary glands – modified sweat glands between the eyelashes</li></ul>Figure 8.1b<br />Slide 8.3c<br />Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings<br />
  21. 21. Accessory Structures of the Eye<br /><ul><li>Conjunctiva
  22. 22. Membrane that lines the eyelids
  23. 23. Connects to the surface of the eye
  24. 24. Secretes mucus to lubricate the eye</li></ul>Slide 8.4a<br />Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings<br />
  25. 25. Accessory Structures of the Eye<br /><ul><li>Lacrimal apparatus
  26. 26. Lacrimal gland – produces lacrimal fluid
  27. 27. Lacrimal canals – drains lacrimal fluid from eyes</li></ul>Figure 8.1a<br />Slide 8.4b<br />Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings<br />
  28. 28. Accessory Structures of the Eye<br /><ul><li>Lacrimal sac – provides passage of lacrimal fluid towards nasal cavity</li></ul>Figure 8.1a<br />Slide 8.4c<br />Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings<br />
  29. 29. Accessory Structures of the Eye<br /><ul><li>Nasolacrimal duct – empties lacrimal fluid into the nasal cavity</li></ul>Figure 8.1a<br />Slide 8.4d<br />Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings<br />
  30. 30. Function of the Lacrimal Apparatus<br /><ul><li>Properties of lacrimal fluid
  31. 31. Dilute salt solution (tears)
  32. 32. Contains antibodies and lysozyme
  33. 33. Protects, moistens, and lubricates the eye
  34. 34. Empties into the nasal cavity</li></ul>Slide 8.5<br />Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings<br />
  35. 35. Extrinsic Eye Muscles<br /><ul><li>Muscles attach to the outer surface of the eye
  36. 36. Produce eye movements</li></ul>Figure 8.2<br />Slide 8.6<br />Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings<br />
  37. 37. Structure of the Eye<br /><ul><li>The wall is composed of three tunics
  38. 38. Fibrous tunic – outside layer
  39. 39. Choroid – middle layer
  40. 40. Sensory tunic – inside layer</li></ul>Figure 8.3a<br />Slide 8.7<br />Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings<br />
  41. 41. The Fibrous Tunic<br /><ul><li>Sclera
  42. 42. White connective tissue layer
  43. 43. Seen anteriorly as the “white of the eye”
  44. 44. Cornea
  45. 45. Transparent, central anterior portion
  46. 46. Allows for light to pass through
  47. 47. Repairs itself easily
  48. 48. The only human tissue that can be transplanted without fear of rejection</li></ul>Slide 8.8<br />Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings<br />
  49. 49. Choroid Layer<br /><ul><li>Blood-rich nutritive tunic
  50. 50. Pigment prevents light from scattering
  51. 51. Modified interiorly into two structures
  52. 52. Cilliary body – smooth muscle
  53. 53. Iris
  54. 54. Pigmented layer that gives eye color
  55. 55. Pupil – rounded opening in the iris</li></ul>Slide 8.9<br />Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings<br />
  56. 56. Sensory Tunic (Retina)<br /><ul><li>Contains receptor cells (photoreceptors)
  57. 57. Rods
  58. 58. Cones
  59. 59. Signals pass from photoreceptors via a two-neuron chain
  60. 60. Bipolar neurons
  61. 61. Ganglion cells
  62. 62. Signals leave the retina toward the brain through the optic nerve</li></ul>Slide 8.10<br />Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings<br />
  63. 63. Neurons of the Retina<br />Figure 8.4<br />Slide 8.11<br />Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings<br />
  64. 64. Neurons of the Retina and Vision<br /><ul><li>Rods
  65. 65. Most are found towards the edges of the retina
  66. 66. Allow dim light vision and peripheral vision
  67. 67. Perception is all in gray tones</li></ul>Slide 8.12a<br />Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings<br />
  68. 68. Neurons of the Retina and Vision<br /><ul><li>Cones
  69. 69. Allow for detailed color vision
  70. 70. Densest in the center of the retina
  71. 71. Fovea centralis – area of the retina with only cones
  72. 72. No photoreceptor cells are at the optic disk, or blind spot</li></ul>Slide 8.12b<br />Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings<br />
  73. 73. Cone Sensitivity<br /><ul><li>There are three types of cones
  74. 74. Different cones are sensitive to different wavelengths
  75. 75. Color blindness is the result of lack of one cone type</li></ul>Slide 8.13<br />Figure 8.6<br />Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings<br />
  76. 76. Lens<br /><ul><li>Biconvex crystal-like structure
  77. 77. Held in place by a suspensory ligament attached to the ciliary body</li></ul>Figure 8.3a<br />Slide 8.14<br />Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings<br />
  78. 78. Internal Eye Chamber Fluids<br /><ul><li>Aqueous humor
  79. 79. Watery fluid found in chamber between the lens and cornea
  80. 80. Similar to blood plasma
  81. 81. Helps maintain intraocular pressure
  82. 82. Provides nutrients for the lens and cornea
  83. 83. Reabsorbed into venous blood through the canal of Schlemm</li></ul>Slide 8.15a<br />Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings<br />
  84. 84. Internal Eye Chamber Fluids<br /><ul><li>Vitreous humor
  85. 85. Gel-like substance behind the lens
  86. 86. Keeps the eye from collapsing
  87. 87. Lasts a lifetime and is not replaced</li></ul>Slide 8.15b<br />Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings<br />
  88. 88. Lens Accommodation<br /><ul><li>Light must be focused to a point on the retina for optimal vision
  89. 89. The eye is set for distance vision (over 20 ft away)
  90. 90. The lens must change shape to focus for closer objects</li></ul>Slide 8.16<br />Figure 8.9<br />Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings<br />
  91. 91. Images Formed on the Retina<br />Figure 8.10<br />Slide 8.17<br />Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings<br />
  92. 92. Visual Pathway<br /><ul><li>Photoreceptors of the retina
  93. 93. Optic nerve
  94. 94. Optic nerve crosses at the optic chiasma</li></ul>Slide 8.18a<br />Figure 8.11<br />Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings<br />
  95. 95. Visual Pathway<br /><ul><li>Optic tracts
  96. 96. Thalamus (axons form optic radiation)
  97. 97. Visula cortex of the occipital lobe</li></ul>Slide 8.18b<br />Figure 8.11<br />Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings<br />
  98. 98. Eye Reflexes<br /><ul><li>Internal muscles are controlled by the autonomic nervous system
  99. 99. Bright light causes pupils to constrict through action of radial and ciliary muscles
  100. 100. Viewing close objects causes accommodation
  101. 101. External muscles control eye movement to follow objects
  102. 102. Viewing close objects causes convergence (eyes moving medially)</li></ul>Slide 8.19<br />Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings<br />

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