Histology Of The Eye And Ear Flashcards
Aqueous humor is secreted into the posterior chamber by the _____.
Fluid passes through the pupil to enter the _____. Excess fluid is taken up by ____.
The aqueous humor fx to provide _____ to avascular structures and maintain ocular shape.
Increased ____ caused by excessive aqueous humor production or impedance of removal is a risk factor for glaucoma.
Ciliary processes
Anterior chamber
Limbus apparatus (trabecular network and canal of Schlemm)
Nutrients and O2
Intraocular pressure
The lens is a transparent, avascular, bi-con caved structure suspended by ____.
What are the three components of the lens?
Zonular fibers
Capsule
Subcapsular lens epithelium: stem cells on periphery proliferate and migrate to make mature lens fibers (rate decreases with age; vision worsens)
Lens fibers: filled with crystalline and lose all organelles as they mature/migrate
Elasticity of the lens is caused by tension from the ____ and transmitted via zonular fibers to allow the lens to change its shape.
Loss of lens elasticity with age
Loss of transparency of lens or capsule
Ciliary body
Presbyopia
Cataracts
_____ is a layer of simple cuboidal epithelial cells resting on Bruch’s membrane of the choroid. This serves as the _____ barrier.
Fx?
Retinal pigmented layer (RPE)
Blood-neural retinal barrier
Absorbs stray light
Phagocytoses membranous discs shed from rods and cones
Isomerizes trans retinal to cis retinal, transporting it back to photoreceptors
Three components of the retinal layer?
Retinal pigmented layer
Neural retina: contains photosensory cells; no lymphatics
Optic disc: blind spot in retina where optic nerves from ganglion layer exit the eye (no rods and cones)
Rod cells are more ____ to light than cone cells.
____ is the highest concentration of cones; avascular, and surrounded by macula lutea.
What are the visual pigments in rods and cones?
No photoreceptors at _____.
Sensitive
Fovea centralis
Rhodopsin; iodopsin
Optic disc (optic N region)
What is the general structures of rods and cones?
Outer segment: photosensitive part with series of plasma membrane discs; discs connected to inner segment by cilium; discs shed and phagocytosis by RPE
Connecting stalk: contains basal body of cilium
Inner segment: major organelles
____ is an autosomal dominant genetic disorder caused by mutation in ____ gene; this is a tumor suppressor gene.
Causes what?
Retinoblastoma
Rb
Malignant tumor of retina that develops in children younger than 5
Leukocoria: abnormal white light reflection off retina
Strabismus: misalignment of eyes
What are the four parts of the inner ear?
Auditory proton: cochlea
Vestibular portion: semicircular canals, utricle, saccule
Bony labyrinth: interconnected cavities and canals within bone
Membranous labyrinth: within bony labyrinth; contains small sacs forming continuous spaces enclosed by epithelium
What are the three parts of the membranous labyrinth?
What do they contain?
Endolymphatic space: within membranous labyrinth; endolymph (high K+ fluid); reabsorbed by dural sinuses with CSF
Perilymphatic space: between bony and a membranous labyrinth; perilymph fluid enters into CNS and subarachnoid space
Corticolymphatic space: within organ of Corti
The ___ is composed of hair cells, inner and outer phalangeal cells, and pillar cells
Stereocilia of hair cells embedded in the overlying ____ extend from the spiral lamina.
____ vibrates with sound causing deflection of stereocilia attached to tectorial membrane; this initiates neural transduction carried by ____ nerve.
Organ of corti
Tectorial membrane
Basilar membrane
Cochlear N
Stapes moves the ____ causing fluid pressure wave formation in perilymph.
Wave distorts _____ and causes a pressure wave within endolymph of scala media.
This causes displacement of ____ and initiates a signal.
The remaining pressure in the perilymph is transferred to the scala tympani and exits via the _____.
Oval window
Vestibular membrane
Basilar membrane
Round window
There are three semicircular canals filled with ____ and connected to a utricle.
Innervated hair cells with stereocilia are attached to the ____, which is the cap on the ampullaris at the end of the canals.
The ____ is displaced by fluid motion within the canal and serves as sensors of _____.
Endolymph
Cupulla
Cupulla
Rotational velocity
_____ are special sebaceous glands; secretion prevents evaporation of tears; blockage of these gland leads to ____.
____ are sebaceous glands of the eyelashes; infection of theses is called a stye
Tarsal glands
Chalazion
Zeis gland
____ gland produces tears; it is located beneath the conjunctiva; made of ___ and drains into the nasolactimal duct.
____ is a thin mucous membrane of stratified columnar epithelium with goblet cells that lines the space between the inner eyelid and ends laterally to the cornea.
Lacrimal gland
Tubuloacinar serous glands
Palpebral and bulbar conjunctiva
The formation of the eye begins with an evagination of ____ from the forebrain forming optic vesicles -> invagination of optic vesicles forms the optic cup.
Optic vesicles induce the overlying ectoderm to form a ____.
Inner layer of optic cup forms ____, outer layer forms ____, outer mesenchyme forms ______.
Rim of optic cup forms ____.
Ectoderm overlying lens vesicle forms ___.
Blood vessels enter groove called ____.
Neruoectoderm
Lens vesicle
Neural retina
Retinal pigmented epithelium
Choroid, sclera, cornea
Iris and ciliary body
Lid and outer corneal epithelium
Optic fissure
What are the three basic layers of the eye?
Corneoscleral
Vascular coat
Retina
What are the parts of the corneoscleral layer?
Sclera: dense CT; attaches to extrinsic muscles; pierced by BV and posteriorly by optic N
Cornea: anterior surface is continuous with sclera
What are the layers of the vascular coat layer?
Choroid: pigmented, absorbs scattered light; rich in BV lined with fenestrated capillaries that provide nutrients to the retina
Stroma of ciliary body: contains ciliary muscle
Stroma of iris: contractile diaphragm of pupil
What are the layers of the retina layer?
Epithelium of ciliary body and iris
Neural retina: photoreceptors and support cells
Retinal pigmented epithelium: absorbs light, prevents reflections, blood retinal barrier, phagocytosis
Anterior chamber?
Posterior chamber?
Vitreous chamber?
Space between cornea and iris
Space between posterior surface of iris and anterior surface of lens; filled with aqueous humor
Space between posterior surface of lens and neural retina; filled with vitreous humor to maintain shape
The cornea is the chief refractive element of the eye. What are the layers of the cornea?
Corneal epithelium: nonkeratinized stratified squamous; highly innervated (sensitive to touch); get O2 and nutrients to stroma from lacrimal glands
Bowmans membrane: anterior basement membrane
Corneal stroma: avascular; fibroblastic
Descemets membrane: posterior basement membrane
Corneal endothelium: simple squamous ; contains Na/ATPase pumps to transport nutrients from aqueous humor to stroma
What are the three parts of the vascular coat layer?
Choroid layer?
Choroid, ciliary body, iris
Inner vascular layer and Bruch’s membrane
The anterior vascular coat becomes the ____ between the iris and choroid.
What does the ciliary muscle do?
Ciliary processes?
Ciliary body
Smooth muscle originating at corneoscleral junctions; drives accommodation of the lens (changing shape)
Secretion of aqueous humor and formation and anchoring of zonular fibers forming suspensory L of lens
Iris forms ____ in front of the lens. It arises form the anterior border of the ____. Contains dilator (radial band) and sphincter pupillae (circular band) muscles and _____.
Contractile diaphragm
Ciliary body
Posterior pigmented epithelium
What are the ten layers of the retina from superficial to deep?
- Retinal pigmented epithelium
- Rod and cones
- Outer limiting membrane
- Outer nuclear layer
- Outer plexiform layer
- Inner nuclear layer
- Inner plexiform layer
- Ganglion layer
- Layer of optic nerve fibers
- Inner limiting membrane
The ____ is a spiral space within bone containing the cochlear duct
Cochlear duct divides the cochlear canal into three soft tissue lined compartments called what?
Cochlear canal
Scala media: contains endolymph that is reabsorbed by dural venous sinuses by endolymphatic duct and sac; lateral wall is stria vascularis and is the source of endolymph
Scala vestibuli: contains perilymph moved by stapes at ovale window
Scala tympani: connected to round window
Where is the organ of corti?
____ is the inner spiraling bony shelf serving as support for tectorial membrane and spiral ganglia
Floor of scala media resting on basilar membrane
Outer spiral lamina
Vestibule contains the ____ and ____.
They contain a macula comprised of a cluster of hair cells with stereocilia with overlying ____. This membrane is covered with calcium carbonate protein crystals called otoconia.
Serves as sensors for gravity and _____.
Saccule and utricle
Otolithic membrane
Linear acceleration
