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Special senses pt 1

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