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Special Senses: Vision!
Transcript of Special Senses: Vision!
smell/taste, hearing, and sight.
special sense receptors:
of the Eye
cover, protect eye
memb. lining eyelids/ball, secretes lube mucus.
gland and ducts
secretes salty tears w/ lysozyme
subject to inflammation
Extrinsic Eye mm
produce eye movements, i.e., tracking/convergence
Internal Structures: the Eyeball
hollow, fluid-filled ball w/ lens that separates ant/post chambers
transparent w/ pain receptors
blood and dark pigment
holds lens via ciliary zonule
2 sheets, pigmented (outer), and neural (inner)
has rods/cones (photoreceptors) all over
detect motion in dim light, peripheral
red, blue, green, visual acuity in bright light (fovea centralis)
optic nerve (axons) exit eye (blind spot)
Physiology of Vision
Path of Light/Refraction
stacked inside rods/cones
absorb light E, change shape, cause AP
need vit. A to create a protein that detects light
light bends when passing through diff. densities.
cornea, aq. humor, lens
(variable), vitreous humor, retina
bend lens to focus light from close image
reversed, upside dn, sm.
impulse from optic nerve to optic chiasma (x) to optic tract to visual cortex
info from lateral side of eye on same side of brain and medial side of contralateral eye.
eyes move medially to look at something close
accomodation pup. reflex:
pupils constrict to look at something close
inflammation nasal cavity blocks drainage.
lack of vit. A
nonfxning red/green cones
hard, cloudy lens
incr. P in aq. humor damages retina
lose same side of visual field of both eyes.
Do You Have Emmetropia?
focal plane (image) lands on retina
focal plane in front of retina
eye too long or lens/cornea too curved
correct w/ concave lens
focal plane behind retina
from short eyeball, flattened lens
correct w/ convex lens
vision loss in area where retina no longer absorbing light