MCAT Question A Day - 6/29/13 - Answer!
The optic disc is the site where axons from cells in the retina leave the eye and where the optic nerve originates. Since there is no room for any rods or cones at this location, what would you expect to happen when light strikes the optic disc?
A. The visual image will not be in focus.
B. Impulses along the optic nerve will speed up.
C. Impulses along the optic nerve will slow down.
D. No visual image will form.
The correct answer is (D). If there are no receptors, no electrical signals will be initiated and no visual image will form. Impulses along the optic nerve will not occur at all.
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