neurobio 915 ch 9 of Bear's book: the eye part 1 (cornea sclera retina fovea lens bipolar cell

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mikepl103
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267611
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neurobio 915 ch 9 of Bear's book: the eye part 1 (cornea sclera retina fovea lens bipolar cell
Updated:
2014-03-30 08:56:35
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neurobio 915 Bear book eye part cornea sclera retina fovea lens bipolar cell ganglion amacrine cone rod rhodopsin
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2014,biology,neurobiology
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neurobio 915 ch 9 of Bear's book: the eye part 1 (cornea, sclera, retina, fovea, lens, bipolar cell, ganglion cell, amacrine cell, cone cell, rod cell, rhodopsin)
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  1. what is the sclera?
    the white of the eye
  2. what is the optic disk?
    the region of the eye where the optic nerve fibers exit the retina
  3. what is the fluid located between the cornea and the lens called?
    aqueous humor
  4. what is the fluid located behind the lens called?
    vitreous humor
  5. the lens is suspended by ligaments attached to the ____ _____
    ciliary muscles
  6. what is the site of the most refractive power in the eye?
    the cornea
  7. what is the focal distance?
    the distance from the refractive surface to the point where parallel light rays converge
  8. what is a diopter?
    the recpirocal of the focal distance in meters is a unit of measurement called the diopter
  9. what is accomodation
    changing the shape of the lens
  10. what does visual acuity depend on?
    it depends especially on the spacing of photoreceptors in the retina and the precision of the eye's refraction
  11. true or false, the bipolar cel is the only source of output from the retina
    false, the ganglion cell is the only source of output from the retina
  12. the retina exhibits what kind of organization?
    laminar organization, ie, the cells are organized in layers (inside-out layers)
  13. diff. between rods and cones
    rods detect black and white; they are more sensitive than cones in nightime lighting. cones detect color; they are more sensitive than rods in daytime lighting.

    rods only ontain one type of pigment, but there are three types of cone, each containing a different pigment.
  14. what is characteristic of the retinal periphery?
    it contains a higher ratio of rods to cones. it also has a higher atio of photoreceptors to ganglion cells. Ther result of this is that the peripheral retina is more sensitive to light
  15. what is the region of the retina that is most highly specialized for high0resolution vision?
    the fovea
  16. in the dark, are the sodium channels opened or closed in rods? What is the molecular basis behind this? What is this movement of positive charge across the membrane called?
    they are opened. sodium channels are stimulated to open (they are gated) by an intracellular second messenger called cGMP. Evidently, cGMP is continually produced in the photoreceptor by the enzyme guanylyl cyclase, keeping the Na channels open. The movement of positive charge across the membrane is called the dark current, since it occurs when the eye isn't exposed to light.
  17. What occurs in regard to cGMP in rods when the rod is exposed to light.
    Light reduces cGMP, causing the Na channels to lose, and the membrane potential becomes more negative.
  18. photoreceptors __________ in response to light
    hyperpolarize
  19. what is the light-absorbing pigment in rods called?
    rhodopsin
  20. what is the receptor protein of the rhodopsin molecule called?
    opsin
  21. rhodopsin can be thought of as a combination of two things. What are these two things?
    it can be thought of as a receptor protein with a pre-bound chemical agonist
  22. what is the prebound agonist of the rhodopsin molecule called?
    retinal

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