5.1 neuro - vision Flashcards
what are the three layers (tunics) of the eyeball
outer fibrous, intermediate vascular layer, inner neural layer
what are they layers of the eyeball also referred to as
tunics
fibrous tunic (what, made of what)
the outer layer of the eyeball, strong dense collagenous connective tissue layer
what are the two division of the fibrous tunic
sclera, cornea
is the cornea vascular or avascular
avascular
cornea (what, function)
transparent anterior surface of the fibrous tunic, main refractive index of the eye
sclera (what, function)
tough opaque outer covering, forms the white part of the eye, provides protection, maintains the shape of the eyeball, serves as the site of muscle attachment for the extrinsic muscles
what are the three parts of the vascular tunic
choroid, ciliary body, iris
what is the vascular tunic
middle layer of the eyeball
what is the choroid of the vascular tunic (vascular/avascular, function)
highly vascularized, provides nutrients to the posterior (deep) surface of the retina, lines most of the sclera
what is the ciliary body
anterior portion of the vacular tunic
what does the ciliary body consist of
ciliary process and ciliary muscle
what does the ciliary process do
contains capillaries and secretes aqueous humor
what extends from the ciliary process and where do they attach
zonular fibers (suspensory ligaments) that attach to the lens
what do ciliary muscles do
contraction or relaxation of the ciliary muscles changes the tension on the zonular fibers, which alters the shape of the lense, adapting it for near and far vision
how are ciliary muscles arranged
longitudinal, oblique, and circularly
what is the iris
colored part of the eye
what muscles control the diameter of the pupil
sphincter and dilator muscles in the iris
what proteins are in the lens and what do they do
crystallin, make up refractive media of the lens, arranged like layers of an onion
is the lens of the eye vascular or avascular
avascular
are constrictor pupillae (circular) innervated by sympathetic or parasympathetic fibers
parasympathetic
are dilator pupillae (radial) innervated by sympathetic or parasympathetic fibers
sympathetic
what is the function of the iris
muscles control the diameter of the pupil
what two layers does the retina consist of
pigmented layer, neural layer
what is the pigmented layer of the retina and what does it do
sheet of melanin-containing epithelial cells, helps to absorb stray light rays
what are the 3 layers of retinal neurons
photoreceptive layer, bipolar cell layer, ganglion cell layer
what two types of cells are present in the bipolar retinal neuron layer and what do they do
horizontal cells and amacrine cells - modify the signal
what are the two types of photoreceptors
rods and cones
what do rods do
allow us to see in dim light
what do cones do
bright light stimulates the cones which produce color vision
what does the photoreceptor layer of the retina do
detect light
what does the bipolar layer of the retina do
relay to ganglion neurons
what does the ganglion layer of the retina do
output to the thalamus
what is the retinal pigmented epilthelium
nonvisual portion, absorbs stray light and helps keep vision clear
what is the optic disc
where CN II exits the eyeball
what is CN II formed of
collected axons of the ganglion layer neurons
what does the central retinal artery supply
branches to supply nourishment to retina
what veins and arteries travel within the optic nerve
central retinal artery, branch of the ophthalmic artery, and the central retinal vein
what and where is the macula latea
yellow spot, fewer blood vessels, in in the exact center of the posterior portion of the retina, at the visual axis of the eye
what portion of the eyeball does the retina cover
posterior 3/4
what and where is the fovea centralis
small depression at the center of the macula lutea, contains only cones and is the area of highest visual acuity or resolution
are there rods or cones in the optic disc
neither, blind spot
what does the interior cavity of the eye consist of
two fluid filled cavities
anterior cavity: between the cornea and lens, contains aqeous humor
posterior cavity: vitreous cavity / chamber, more gel-like, helps hold the retina in place
what is the purpose of vitreous humor in the posterior cavity
supports the retina and lens
list the light pathway through the eye in order
cornea, aqueous humor, pupil, lense, vitreous humor, ganglion cell layer (retina), rods and cones (retina)
list the visual information pathway for vision in order
rods and cones, ganglion cell layer, optic nerve, optic chiasm, optic tract, lateral geniculate body, visual cortex area 17
do gangion cell axons cross the midline at the optic chiasm
half do half don’t
