20. Visual tracts Flashcards
what is the fxn of the tarsal (meibomian) glands
special sebaceous glands
secretion retards evaporation of tears
-if blocked ==> chalazion
what is the name for the infectino of sebaceous glands of eyelashed
stye
whaat is the lacrimal gland
makes tears
= made of tubuloacinar serous glands
-about 12 ducts into upper lid & tears drain into nasolacrimal duct
what is the histological feature of palpebral & bulbar conjunctiva
stratified columnar epithelium w/ goblet cells
btn inner eyelid & stop lateral to cornea
what is the ant chamber
space btn cornea & iris
what is the post chamber
space btn post surfave of iris & ant surface of lens
what is the vitreous chamber
space btn post surface of lens & neuronal retina
-filled with vitreous humor (hep maintain shapde)
=99% water w proteins & hyaluronan
what is the fibrous tunic
what is the vascular tunic/uvea
what makes up the retina (internal layer)
what is the corneoscleral coat
sclera: thick fibrous opaque layer pierced by BVs, N & optic N
cornea: refractive element of the eye; continuous with sclera = 5 layers
what are the 5 layers of the cornea
corneal epithelium
bowman’s membrane
corneal stroma (avascular)
descemet’s membrane
corneal EDNOthelium
what is the vascular coat
made of choroid
ciliary body
& iris
what are the structural components of the lens
capsule: flexible/elastic ECM
subcapsular lens epithelium: cells on periphery proliferate & migrate to make mature lens fibers (decrease rate w/ age)
lens fibers: filler with crystallins & lose all organelles
what is accommodation
adjustment of eyes for seeing object in distance
-by ciliary M (flatten/thicken)
tension of ciliary body send via zonalar polls -> change shape
what is presbyopia
loss of lens elasticity w age
characteristics of the retinal pigmented layer
sinmpe cuboidal epitheliial cells
=blood- neuroal retinal
what is the neural retina
photosensory cells here
no lymphatics
what visual pigments do rods and cones have
rods: rhodopsin
cones: iodopsin
what is the fovea centralis
highest [cones]
visual acuity = sharpest (drops in outer retinal structures)
no vessels, cell bodies and axons
what is the macula lutea
surrounds fovea
antioxidant properties & short wave UV filter
-protects cones of fovea
what is the optic disc
at head of optic N
ganglion axons from all of retina converge & dive
=no photoreceptors = blind spot
explain the location of the optic N
axons of retinal ganglion cells
penetrate choroid & sclera and travel to brain (as they pass thru sclera they become myelinated)
what are the zones of the visual fields
binocular: broad central region
monocular: R/L (only seen by corresponding eye
image formed on retina is —-
inverted in both lateral & vertical dimension
