Ch8ppt special senses 1

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Ch8ppt special senses 1

  1. 1. PowerPoint® Lecture Slide Presentation by Patty Bostwick-Taylor, Florence-Darlington Technical College Special Senses 8 PART A Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
  2. 2. The Senses  Special senses  Smell  Taste  Sight  Hearing  Equilibrium Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
  3. 3. Structure of the Eye Figure 8.4a Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
  4. 4. Structure of the Eye: The Fibrous Layer  Sclera  White connective tissue layer  Seen anteriorly as the “white of the eye”  Cornea  Transparent, central anterior portion  Allows for light to pass through  Repairs itself easily  The only human tissue that can be transplanted without fear of rejection Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
  5. 5. Structure of the Eye: Vascular Layer  Choroid is a blood-rich nutritive layer in the posterior of the eye  Pigment prevents light from scattering  Modified anteriorly into two structures  Ciliary body—smooth muscle attached to lens  Iris—regulates amount of light entering eye  Pigmented layer that gives eye color  Pupil—rounded opening in the iris Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
  6. 6. Structure of the Eye: Sensory Layer  Retina contains two layers  Outer pigmented layer  Inner neural layer  Contains receptor cells (photoreceptors)  Rods  Cones Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
  7. 7. Structure of the Eye: Sensory Layer  Signals leave the retina toward the brain through the optic nerve  Optic disc (blind spot) is where the optic nerve leaves the eyeball  Cannot see images focused on the optic disc Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
  8. 8. Structure of the Eye: Sensory Layer Figure 8.5a Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
  9. 9. Structure of the Eye: Sensory Layer  Neurons of the retina and vision  Rods  Most are found towards the edges of the retina  Allow dim light vision and peripheral vision  All perception is in gray tones Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
  10. 10. Structure of the Eye: Sensory Layer  Neurons of the retina and vision  Cones  Allow for detailed color vision  Densest in the center of the retina  Fovea centralis—area of the retina with only cones  No photoreceptor cells are at the optic disc, or blind spot PLAY The Eye: The Retina Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
  11. 11. Structure of the Eye: Sensory Layer  Cone sensitivity  Three types of cones  Different cones are sensitive to different wavelengths  Color blindness is the result of the lack of one cone type Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
  12. 12. Sensitivities of Cones to Different Wavelengths Figure 8.6 Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
  13. 13. Lens  Biconvex crystal-like structure  Held in place by a suspensory ligament attached to the ciliary body PLAY The Eye: Lens and Retina Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
  14. 14. Lens Figure 8.4a Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
  15. 15. Lens  Cataracts result when the lens becomes hard and opaque with age  Vision becomes hazy and distorted  Eventually causes blindness in affected eye Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
  16. 16. Lens Figure 8.7 Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
  17. 17. Two Segments, or Chambers, of the Eye  Anterior (aqueous) segment  Anterior to the lens  Contains aqueous humor  Posterior (vitreous) segment  Posterior to the lens  Contains vitreous humor Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
  18. 18. Anterior Segment  Aqueous humor  Watery fluid found between lens and cornea  Similar to blood plasma  Helps maintain intraocular pressure  Provides nutrients for the lens and cornea  Reabsorbed into venous blood through the scleral venous sinus, or canal of Schlemm PLAY The Eye: Interior Parts of the Eye Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
  19. 19. Posterior Segment  Vitreous humor  Gel-like substance posterior to the lens  Prevents the eye from collapsing  Helps maintain intraocular pressure PLAY The Eye: Posterior Cavity Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
  20. 20. Pathway of Light Through the Eye  Light must be focused to a point on the retina for optimal vision  The eye is set for distance vision (over 20 feet away)  Accommodation—the lens must change shape to focus on closer objects (less than 20 feet away) Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
  21. 21. Pathway of Light Through the Eye Figure 8.9 Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
  22. 22. Pathway of Light Through the Eye  Image formed on the retina is a real image  Real images are  Reversed from left to right  Upside down  Smaller than the object Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
  23. 23. Images Formed on the Retina Figure 8.10 Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
  24. 24. A Closer Look  Emmetropia—eye focuses images correctly on the retina  Myopia (nearsighted)  Distant objects appear blurry  Light from those objects fails to reach the retina and are focused in front of it  Results from an eyeball that is too long Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
  25. 25. A Closer Look  Hyperopia (farsighted)  Near objects are blurry while distant objects are clear  Distant objects are focused behind the retina  Results from an eyeball that is too short or from a “lazy lens” Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
  26. 26. A Closer Look  Astigmatism  Images are blurry  Results from light focusing as lines, not points, on the retina due to unequal curvatures of the cornea or lens Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
  27. 27. Homeostatic Imbalances of the Eyes  Night blindness—inhibited rod function that hinders the ability to see at night  Color blindness—genetic conditions that result in the inability to see certain colors  Due to the lack of one type of cone (partial color blindness)  Cataracts—when lens becomes hard and opaque, our vision becomes hazy and distorted Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
  28. 28. Homeostatic Imbalances of the Eyes  Glaucoma—can cause blindness due to increasing pressure within the eye  Hemianopia—loss of the same side of the visual field of both eyes; results from damage to the visual cortex on one side only Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
  29. 29. The Ear  Houses two senses  Hearing  Equilibrium (balance)  Receptors are mechanoreceptors  Different organs house receptors for each sense Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
  30. 30. Anatomy of the Ear  The ear is divided into three areas  External (outer) ear  Middle ear (tympanic cavity)  Inner ear (bony labyrinth) Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
  31. 31. Anatomy of the Ear Figure 8.12 Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
  32. 32. The External Ear  Involved in hearing only  Structures of the external ear  Auricle (pinna)  External acoustic meatus (auditory canal)  Narrow chamber in the temporal bone  Lined with skin and ceruminous (wax) glands  Ends at the tympanic membrane Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
  33. 33. The Middle Ear (Tympanic Cavity)  Air-filled cavity within the temporal bone  Only involved in the sense of hearing Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
  34. 34. The Middle Ear (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 Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
  35. 35. Bones of the Middle Ear (Tympanic Cavity)  Three bones (ossicles) span the cavity  Malleus (hammer)  Incus (anvil)  Stapes (stirrip)  Function  Vibrations from eardrum move the malleus  anvil  stirrup  inner ear Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
  36. 36. Anatomy of the Ear Figure 8.12 Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
  37. 37. Inner Ear or Bony Labyrinth  Includes sense organs for hearing and balance  A maze of bony chambers within the temporal bone  Cochlea  Vestibule (static equilibrium – position of head)  Semicircular canals (dynamic equilibrium – movement of head) Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
  38. 38. Organs of Equilibrium Figure 8.14a–b Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
  39. 39. Mechanism of Hearing Figure 8.16a Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
  40. 40. Olfaction—The Sense of Smell  Olfactory receptors are in the roof of the nasal cavity  Neurons with long cilia  Chemicals must be dissolved in mucus for detection  Impulses are transmitted via the olfactory nerve  Interpretation of smells is made in the cortex Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
  41. 41. The Sense of Taste  Taste buds house the receptor organs  Location of taste buds  Most are on the tongue  Soft palate  Cheeks Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
  42. 42. Taste Buds Figure 8.18 Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
  43. 43. Taste Sensations  Sweet receptors (sugars)  Saccharine  Some amino acids  Sour receptors  Acids  Bitter receptors  Alkaloids  Salty receptors  Metal ions Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
  44. 44. Chemical Senses: Taste and Smell  Both senses use chemoreceptors  Stimulated by chemicals in solution  Taste has four types of receptors  Smell can differentiate a large range of chemicals  Both senses complement each other and respond to many of the same stimuli Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
  45. 45. Developmental Aspects of the Special Senses  Formed early in embryonic development  Eyes are outgrowths of the brain  All special senses are functional at birth Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings

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