149 & 150 Special Sense: Vision Flashcards
most of the refraction of light takes place in the
cornea
how is the aqueous humor formed
ciliary body secretes Na, which then pulls in water and Cl, other nutrients enter ia facilitated diffusion
what is the flow of aqueous humor
flows through pupil, angle of anterior chamber, Trabecular meshwork, canal of schlemm, aqeuous ceins
increased intraocular pressure leads to
glaucoma
if you hace a closed angle, when will you hae symptoms
in the dark, when the eyes try to dialate
what allows you to accomodate for far target
ciliary muscles relax, suspensory ligament contract
what muscle helps with ocular conergence
medial rectus
what is presbyopia
loss of accomodation of lens (seen with age)
what is cycloplegia
loss of accomodation due to loss of ciliary muscle (atropine)
Constriction _____ the angle of the anterior chamber
increases
what is the pathway for pupillary reflex
light, CN II, pretectal area, EDINGER_WESTPHAL NUCLEUS, CN III, ciliary ganglion, ciliary muscles, constrictor pupilae
what three things are in depth perception
size of object, moing parallax, steropsis
where is itamin A stored
pigmented layer
what is the light sensitie pigement in rods
rhodopsin
what is rhodopsin composed of
scotopsin and retinal
the unstimulated retinal is in _____ form
cis
what happens when retinal is conerted to all trans
no longer fits with scotopsin -> bathorrhodopsin -> decays into lumirhodospin-> metarhodopsin
what conerts all trans retinal to cis
isomerase
unstimulated rods are _______
depolarized (Na influx through cGMP gated channels)
upon stimulation with light, rods become
hyperpolarized
destabilization of rhodopsin actiates
transducin
what does transducin actiate
cGMP phosphodiesterase
how can viagra cause blindness
it inhibits phospodiesterase, resulting in the cells staying depolarized and not reacting to light
what inactates metarhodopsin II
rhodopsin kinase
Rods dont see
Red
when is pigment converted to vitamin A
bright light
what role does calcium play in light adaptation
indirectly regualtes cGMP dependent channels
which cells sharpen retinal image
biolar
which cells provide contrast
horizontal
which cells control light senstitivity
amacrine
the output of horizontal cells is always
inhibitory
which cells are responsible for circadia rhythm
ganglion cells
are p or m cells sensitive to color
P (less sensitive overall and does fine details)
what nucleus of hypothalamus controls circadian rhytm
suprachiasmatic nucleus
what area of the thalamus does reflex movement of the eye
pretectal
what area of the brain does rapid directional movement of both eyes
superior colliculi
lateral geniculate nuclei sends fibers to
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