Download Special Senses: Vision

What are your five major
senses?
Special Senses: Vision
External Structures of Eye
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Eye lids
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Eyelashes
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Conjunctiva-thin
membrane under
eyelid
Tear Glands
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Lacrimal glands
produce tears
Tears are dilute
salt solution
Contain lysozyme
to kill bacteria
Drain into nasal
cavity
Structures of Eye
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Sclera- “white of
eyes”;thick layer that
protects eye
Cornea- clear medial
window in sclera;allows
light into eye
Choroid – dark internal
layer of eye; keeps light
from scattering in eye,
keeps inside of eye dark.
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Ciliary body - holds
lens
Lens – bends to
focus light on
correct part of
retina
Iris- pigmented;
contains hole
called pupil which
allows light
through
So how do you actually see?
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Retina – receives and
translates light message into
nerve impulses
Contains photoreceptors called
rods and cones
Messages leave
photoreceptors and pass to
optic nerve, then to occipital
lobe of brain for translation.
Fovea Centralis- Region of the
retina that produces the
sharpest vision.
Blind Spot
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Optic nerve is covered by photoreceptors
Except for optic disc (where optic nerve
leaves eyeball)
Blind spot