visual system Flashcards
the eye
a globe that is filled with fluids
-composed of various layers
3 layers of the eye
outer, middle, and inner layer
outer layer
contains the sclera and cornea
middle layer
choroid with blood vessels and nerves
inner layer
retina
-light sensing part of the eye
2 fluids of the eye
aqueous and vitreous humor
aqueous humor
thin watery fluid
-anterior to lens but between lens and cornea
-contains nutrients for cornea and lens
viterous humor
thick jelly like semifluid
-posterior to the lends but between the lens and retina
-maintains shape of eye
cornea
clear part that we see through
-front of eye
-outermost front
anterior chamber
directly under the cornea
-contains aqueous humor
lens
behind the cornea that changes shape
-helps focus
-gives us the pupil
iris
holding lens in place
-gives us the color
ciliary body
helps tighten or loosen fibers
-lateral to zonula fibers
posterior chamber
small space before/on the side of the lens
-contains aqueous humor
sclera
white of the eye
-outermost layer around the eye
zonula fibers
around lens on the sides to help hold in place
choroid
vascular layer that provides blood supply and nutrients
-vascularized
-between sclera and retina
retina
visual sensing layer that contains rods and cones
-below the choroid layer
optic disk
back of the eyeball where retinal arteries and veins come into
-can create a blindspot
-medial side at the back side of the eye
fovea
area of higher visual ability
-focus
-lateral of the optic disk
rectus tendon
how the eye muscles attach
-on both sides, will have a medial and lateral one
subarachnoid space
following from meninges
-the “window to the CNS”
-at the back side coming off the eye
retinal arteries and veins
runs in alongside the CN 2 and into the retina
optic nerve (CN 2)
at back of the eye and comes inward to the retina
-enters at the optic disk
canal of schlemm
allows for fluids to go into the eye
conjunctiva
tissue that helps hold the eyeball in place of lateral edges
ora serrata
jagged edge where the retina is ending and we will have the ciliary muscle above it
macula
the area surrounding the fovea
-rich in cones but not rods
what are the two photoreceptors of the retina
rods and cones
rods are good for what vision
black, white and gray vision
-night vision
cones are good for what vision
color vision
-high visual acuity
how does stimulation of rods and cones work
the stimulus strokes the rods and cones, graded receptor potentials will occur, excitation is passed to cells of the retina and when the retinal ganglion cells receive the excitation AP are generated
bigger light results in ______________
bigger excitation
retinogeniculostriate pathway
retina to V1
-ganglion cells of CN 2 to optic chiasm, fibers leave lateral geniculate nucleus to the internal capsule and become optic radiations, projects to visual cortex above or below the calcarine sulcus
retinohypothalamic pathway order
retinal ganglion cells axons of CN II pass to the optic chiasm where some decussate and enter either the left or right optic tract. Most fibers in the optic tracts terminate in the lateral geniculate nucleus of the thalamus. From the thalamus, project to internal capsule to optic radiation (V1) to above or below calcarine sulcus (lingual/cuneus gyrus)
light reflexes
bright light directed into one eye causes pupils of both eyes to constrict
accommodation reflex
accommodation- eyes changing shape as we age, why we need reading glasses when we’re older
convergence reflex
convergence- eyes coming together via the medial rectus to focus on a close object (cross-eyed)
