8.4 Vision Flashcards
3 layers of the eye
- outer fibrous (cornea and sclera)
- middle vascular (choroid, iris, ciliary body)
- inner neural (retina)
importance of the aqueous humor
necessary for providing nutrients to the lens and cornea
creates refractive power for the eye
aqueous humor is produced by
ciliary body
what is the total refractive power of the eye? (lens+cornea)
59 Diopters (D=1/meter)
refractive power of the cornea?
42 Diopters
refractive power of the lens?
17 Diopters
light rays from distant objects are
nearly parallel
so we dont need a lot of refraction
what happens to the ciliary muscles/lens/ligaments when you are looking at a distanced object?
ciliary muscles relax
ligamentss tense
lens is flat
ciliary muscle is under _________ control
Parasympathetic
describe what Muller cells are
long glial cells that stretch almost the entire length of the retina
function of Muller cells?
- regulating K+ levels in the extracellular enviroment
- NT uptake
- glycogen storage for energy
- electrical insulation
- protection for neurns
what is the importance of the pigmented layer of the Retina?
- absorbs extra light
- allows transport of vitamin A, Cl- and water
- converts all-trans-retinal to 11-cis-retinal for delivery to the photoreceptors
layers of the retina
- pigmented
- photoreceptors
- outer limiting
- outer nuclear
- outer plexiform
- inner nuclear
- inner plexiform
- ggl
- nerve fibers
- inner limiting
Rods are responsible for
detect light
why are Rods extremely sensitive to light?
they have high amount of Rhodopsin
why Rods have low acuity?
many Rods synaps on a single bipolar cell
where can we find Rods?
peripheral part of the retina
Cones are responsible for
color vision
why Cones have high acuity?
only a few Cones synaps on a bipolar cell
where can we find Cones?
primarly located in the macula with the fovea having the highest density of cones
where is the point of highest visual acuity and why?
fovea
one Cone synapses with one bipolar cell
why do Rods have low acuity?
many rods synaps on one bipolar cell
what is tne main location of Rods?
primarly in the peripheral parts of the retina
why cones are less sensitive to light?
less rhodopsin -> several hundreds photons are needed in order to activate it
