19 Flashcards
Rods will tell you
the absence of light- contrast
Cones will tell you
color and a very sharp image, but you need an abundance of light in order to activate cones.
Light transduction:
rods and cones > bipolar cells > ganglion cells > SCN
Amacrine cell
can help bring a cell to an action potential for the next step- alter the sensitivity to the eye- help that msg be transferred or inhibits it.
Fovea centralis
where we are going to get our clearest, sharpest vision
optic disc
where the signal is received, where the blood vessels to the eye are.
Anterior cavity
aqueous humor, like CSF where this a production point and an exit point.
Aqueous humor is needed for
nutrient and waste transport, fluid cushion, provides pressure to retain shape
Ciliary body is in the
vascular layer
Entrance and Exit point for the aqueous humor:
Enter: Ciliary Body
Exit: scleral venous sinus
Vitreous Humor
Gelatinous- makes sure the structure of the eyeball is maintained- it is not circulated through.
Posterior cavity has
Vitreous Humor
Lens is attached to the ciliary body via
ciliary zonule (ligaments)
Lens:
be able to change to shape of it in response to light and focus light on the retina.
how’s two regions: lens epithelium anteriorly and lens fibers which forms the bulk of lens
Lens fibers are filled with
transparent protein crystallin (needs to be transparent in order for light to go through)
Lens in general become ____ with age.
dense, convex, less elastic (ability to maintain eyeball structure fails; can’t round it out anymore).
Cataracts
clouding of lens (proteins clump over time), can be taken out and restored
When light bends, it is called
refraction (passes through cornea and lens)
Focal point
specific point of intersection of light rays on retina (where we want to converge to get to the retina)
Focal distance
distance between center of lens and focal point
Astigmatism:
condition where light passing through cornea and lens I son t refracted properly; visual image is distorted.
Accommodation:
autonomic adjustment of eye to provide clear vision
lens become rounder to focus on nearby objects
flatter lens allows focus on distant objects
Near vision:
light rays aren’t parallel, lens need to change in order to focus those rays on our retina
Ciliary muscle (arranged in a circle) contracts. letting ligaments go loose, not so much tension, lets it round out.
Distant vision:
Lens flatten, light rays are parallel, ciliary muscle relaxes which causes ligaments to stretch and cause tension
Light at the point at the top is focused on ___
lower retinal surface, upside down, and reversed.
Near sighted means
you can see things close to you, but not far.
Eyeball is too long/deep- when you focus light rays it’s right in front of retina not on it.
Corrected with concave lens