Vert ch 10

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Vert ch 10
2012-03-08 17:44:01
vertebrate physiology

Vert Physiology chapter 10
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  1. What are the modalities of sense? How are they sensed?
    • light, taste, touch, pressure, etc
    • sensory receptors
  2. What do sensory receptors do?
    transduce sensation into impulses to be transmitted to sensory nerves
  3. what do sensory nerves do?
    transmit impulses to the CNS for processing and appropriate response
  4. How are sensory receptors classified?
    according to the type of sensation they transduce & according to the type of sensory info delivered to the brain
  5. List the 5 types of sensory receptors based on type of sensation
    • chemoreceptors
    • photoreceptors
    • thermoreceptors
    • mechanoreceptors
    • nocireceptors
  6. what do chemoreceptors do?
    sense chemical stimuli in the environment of the blood
  7. what do photoreceptors do?
    sense light sensation for vision
  8. what do thermoreceptors do?
    sense heat and cold
  9. what do mechanoreceptors do?
    sense mechanical deformation due to pressure or touch
  10. what do nocireceptors do?
    sense pain
  11. List the 2 types of sensory receptors based on the type of sensory info sent to the CNS
    • proprioreceptors
    • cutaneous receptors
  12. what do proprioreceptors do?
    sense body position and allow for fine motor activity
  13. what do cutaneous receptors do?
    include sensation for touch, pressure, heat, cold and pain
  14. what do special senses mediate?
    sight, hearing and equilibrium
  15. How do phasic receptors work?
    respond to stimuli with a burst of of activity then quickly adapt by decreasing their firing rate
  16. what is sensory adaptation
    ability of phasic receptors to adapt to stimuli
  17. what are tonic receptors?
    receptors that maintain their firing rate in response to stimuli (ex: pain)
  18. what are some physical examples of sensory receptors?
    free nerve endings, pacinian corpuscle, and Meissner's corpuscle
  19. what happens when sensory receptors are stimulated?
    they are depolarized generating a change in the membrane potential called receptor potential or generator potential thus stimulating an action potential in the receptor
  20. how are cutaneous receptors mediated?
    by dendritic nerve endings of different nerves
  21. how is info transmitted from proprioreceptors and pressure receptors?
    proprioreceptors--> spinal cord--> medulla oblongata--> (via lateral leminiscus) thalamus--> postcentral gyrus
  22. what do the eyes do?
    transduce light energy into nerve impulses for vision
  23. what is the sclera?
    outermost layer of the eye, connective tissue seen externally as the white of the eye
  24. what is the cornea?
    continuation of the sclera
  25. how does light pass through the eye?
    through the cornea into the anterior chamber of the eye then through the pupil
  26. what is the iris?
    the smooth muscle that surrounds the pupil
  27. where does light go after passing through the pupil?
    to the lens
  28. what does the iris do?
    increase or decrease diameter of the pupil by constricting (miosis)
  29. how does miosis take place?
    parasympathetic nerve stimulates circular muscle of the iris
  30. what is mydriasis?
    how does it take place?
    • dilation of the pupil
    • sympathetic nerve stimulates radial muscle of the iris
  31. How is the lens of the eye suspended?
    from a muscular process (ciliary body) by the suspensory ligament
  32. what is the space between the iris and the ciliary body?
    posterior chamber
  33. what is the space between the cornea and the iris?
    anterior chamber
  34. what fills the anterior and posterior chambers?
    aqueous humor secreted by ciliary body
  35. what is the purpose for aqueous humor in the anterior chamber?
    provides nutrition for avascular lens and cornea
  36. what is the canal of schlemm?
    where aqueous humor drains to from the anterior chamber
  37. what does the canal of schlemm do with aqueous humor?
    returns it to veinous blood
  38. What happens when aqueous humor is drained inadequately?
    What is this condition called?
    • accessive accumulation of the fluid leading to increase in intraocular pressure
    • glaucoma
  39. what is the danger of glaucoma?
    damage retina and cause loss of vision
  40. what is vitreous humor?
    thick viscous fluid located in the part of the eye behind the lens
  41. where does the light go from the lens?
    to the retina
  42. what is the retina?
    neutral part of the eye
  43. what absorbs light in the retina?
    choroid layer
  44. what happens when light reaches the retina?
    stimulates photoreceptors which activate retinal neurons
  45. what are the photoreceptors in the retina?
    cones and rods
  46. what do the neurons in the retina do?
    contribute fibers that are gathered together exiting the eye at the optic disc as the optic nerve
  47. what happens when normal eyes view an object?
    parallel light rays are refracted by the lens to the focus which is located on the retina
  48. what is accomidation?
    ability of the eyes to keep the retina focused on an object as it moves closer to the eye
  49. how does accomidation occur?
    contraction of ciliary muscle causes the lens to be more rounded and convex resulting in near vision
  50. how does far vision occur?
    ciliary muscle relaxes causing the lens to b flatter and less convex so the eye can focus on objects further away
  51. define visual activity
    sharpness of the eyes (ability to distinguish closely placed dots)
  52. how is 20/20 vision confirmed?
    if the person can stand 20 feet from a Snellen eye chart and read the line marked "20/20"
  53. in nearsightedness (myopia) what is the problem with the eye?
    the eye ball is too long and the image is focused in front of the retina
  54. what is the problem with the eye in farsightedness (hyeropia)?
    the eyeball is too short and the image is focused behind the retina
  55. what causes astigmatism?
    the curvature of the lens and the cornea are not perfectly symmetrical
  56. which type of lense corrects myopia?
    concave lense
  57. what type of lesne corrects hyeropia?
    convex lens
  58. what type of lenses corrects astigmatism?
    a cylindrical lens
  59. what is emmetropia
    normal vision
  60. what activates the photoreceptors (cones and rods) of the retina?
    light reaching the retina. this causes a chemical change in the pigmented molecules of the photoreceptors
  61. What is rhodopsin?
    purple pigment in rods
  62. What does rhodopsin do?
    transmits light in the red and blue regions of the visible spectrum and absorbs light in the green region
  63. what are the 2 components of rhodopsin?
    • retinaldehyde- derived from vitamin A
    • opsin- a protein
  64. what is the bleaching reaction?
    rhodopsin's reaction to light
  65. what are rods primarily responsible for?
    "night vision"
  66. How do eyes adjust in dark rooms?
    pupils dialate to absorb more light and photoreceptors, especially rods, increase their sensitivity to light
  67. what is dark adaptation?
    the eyes ability to adjust to when entering a dark room
  68. What are cones responsible for?
    color vision and greater acuity
  69. explain the trichromatic theory of color vision?
    color vision is the result of the 3 types of cones designated as blue, green or red according to which each type absorbs to allow for color vision
  70. according to the trichromatic theory of color vision what protein is associated with the retinine of the cones?
  71. what happens when viewing an object in daylight?
    the image falls on the fovea centralis of the retina which contains only rods
  72. how do the fibers of the optic nerve decussate?
    • 1/2 to the contralateral side
    • 1/2 to the ipsilateral side
  73. where do optice nerve fibers travel after the optic chiasma?
    up the optic tract to the superior colliculus
  74. what happens in the superior colliculous?
    visual reflexes are processed?
  75. where do the optic nerve fibers in the optic tract synapse?
    at the lateral geniculate nucleus with neurons that end in the occipital lobe
  76. what are interoceptors?
    chemoreceptors that respond to chemical changes in the internal environment
  77. what are externoceptors?
    chemoreceptors that respond to chemical changes in the extrernal environment
  78. what mediates the sense of taste?
    taste buds on the tongue
  79. list the 4 modalities of taste
    sweet sour bitter salty
  80. which region of the tongue tastes sweet things?
    tip of the tongue
  81. what region of the tongue tastes sour things?
    sides of the tongue
  82. what region of the tongue tastes bitter things?
    back of the tongue
  83. what region of the tongue tastes salty things?
    most of the tongue
  84. what is the suggested 5th modality of taste?
    taste for water found only in humans
  85. what causes salty tastes?
    presence of Na+ or other cations
  86. what causes the taste of sour things?
    presence of H+
  87. How are sweet and bitter tastes produced?
    interaction of taste molecules with specific membrane receptor proteins
  88. what receptors are responsible for the sense of smell?
    dendritic endings of sensory neurons located in the nasal cavity
  89. whats different about olfactory neurons?
    they replace themselves every 1-2 months
  90. whats different about sensory receptors for smell?
    they go directly to the cerebral cortex