Neuro - Eye Flashcards
where do most retinal ganglion axon cells terminate
lateral geniculate nucleus
where does the lateral geniculate nucleus relay to
visual cortex
what are secondary function of retinal ganglionic cells
reflexive eye movement
sleep-wake cycle
where do retinal ganglionic axons terminate to control reflexive eye movement
pretectal nucleus
where do retinal ganglionic axons terminate to control sleep-wake cycle
suprachiasmatic nucleus
what are the three layers in the eye
sclera
choroid
retina
what is responsible for the majority of light refraction
cornea
what is accommodation
changing your optical power to focus near and far
what is myopia
where the light is refracted just short of the retina
short-sightedness
what is hyperopia
when the light is refracted refracted to a point behind the retina
long-sightedness
which retinal ganglion cells cross into the lateral hemisphere
those coming from the nasal part of the reitna
where do retinal ganglion cell axons cross
optic chiasm
where contains the highest concentration of photoreceptors
fovea
what is the retina formed from
diencephalon (optic vesicle)
what are the 5 neuronal types in the eye
photoreceptors
bipolar cells
ganglion cells
amacrine cells
horizontal cells
what is located in the outer segment of photoreceptors
discs containing pigment for light detection
where are photopigments regenerated
RPE
what does light detection at the outer segment lead to and what does this allow for
leads to hyperpolarisation
allows for graded responses
where are opsins located
within the membrane of a disc
function of opsins
tune sensitivity to particular wavelength
what does light induced conformational change of opsins lead to
activation of transducin
activation of cGMP hydrolysis
leads to amplification
function of phosphodiesterase in light transduction
converts cGMP into GMP
what does low levels of calcium lead to in terms of cGMP
increase in guanylate cyclase activity - increase cGMP
what does low levels of calcium lead to in terms of rhodopsin kinase
rhodopsin kinase is activated
phosphorylates rhodopsin
leads to arrestin binding /transducin displacement
what are the Na+/Ca2+ ion channels gated by
cGMP
features of rods
low spatial resolution
high sensitivity (1 photon)
features of cones
high spatial resolution
low sensitivity (>100)
less saturation
rapid recovery
colour vision
what does loss of rod and cone function lead to
rod - night blindness
cone - legally blind
