Histology Of The Eye And Ear

Question 1

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.

Answer 1

Ciliary processes

Anterior chamber

Limbus apparatus (trabecular network and canal of Schlemm)

Nutrients and O2

Intraocular pressure

Question 2

The lens is a transparent, avascular, bi-con caved structure suspended by ____.

What are the three components of the lens?

Answer 2

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

Question 3

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

Answer 3

Ciliary body

Presbyopia

Cataracts

Question 4

_____ is a layer of simple cuboidal epithelial cells resting on Bruch’s membrane of the choroid. This serves as the _____ barrier.

Fx?

Answer 4

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

Question 5

Three components of the retinal layer?

Answer 5

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)

Question 6

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 _____.

Answer 6

Sensitive

Fovea centralis

Rhodopsin; iodopsin

Optic disc (optic N region)

Question 7

What is the general structures of rods and cones?

Answer 7

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

Question 8

____ is an autosomal dominant genetic disorder caused by mutation in ____ gene; this is a tumor suppressor gene.

Causes what?

Answer 8

Retinoblastoma

Rb

Malignant tumor of retina that develops in children younger than 5
Leukocoria: abnormal white light reflection off retina

Strabismus: misalignment of eyes

Question 9

What are the four parts of the inner ear?

Answer 9

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

Question 10

What are the three parts of the membranous labyrinth?

What do they contain?

Answer 10

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

Question 11

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.

Answer 11

Organ of corti

Tectorial membrane

Basilar membrane

Cochlear N

Question 12

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 _____.

Answer 12

Oval window

Vestibular membrane

Basilar membrane

Round window

Question 13

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 _____.

Answer 13

Endolymph

Cupulla

Cupulla

Rotational velocity

Question 14

_____ 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

Answer 14

Tarsal glands

Chalazion

Zeis gland

Question 15

____ 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.

Answer 15

Lacrimal gland

Tubuloacinar serous glands

Palpebral and bulbar conjunctiva

Question 16

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 ____.

Answer 16

Neruoectoderm

Lens vesicle

Neural retina

Retinal pigmented epithelium

Choroid, sclera, cornea

Iris and ciliary body

Lid and outer corneal epithelium

Optic fissure

Question 17

What are the three basic layers of the eye?

Answer 17

Corneoscleral

Vascular coat

Retina

Question 18

What are the parts of the corneoscleral layer?

Answer 18

Sclera: dense CT; attaches to extrinsic muscles; pierced by BV and posteriorly by optic N

Cornea: anterior surface is continuous with sclera

Question 19

What are the layers of the vascular coat layer?

Answer 19

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

Question 20

What are the layers of the retina layer?

Answer 20

Epithelium of ciliary body and iris

Neural retina: photoreceptors and support cells

Retinal pigmented epithelium: absorbs light, prevents reflections, blood retinal barrier, phagocytosis

Question 21

Anterior chamber?

Posterior chamber?

Vitreous chamber?

Answer 21

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

Question 22

The cornea is the chief refractive element of the eye. What are the layers of the cornea?

Answer 22

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

Question 23

What are the three parts of the vascular coat layer?

Choroid layer?

Answer 23

Choroid, ciliary body, iris

Inner vascular layer and Bruch’s membrane

Question 24

The anterior vascular coat becomes the ____ between the iris and choroid.

What does the ciliary muscle do?

Ciliary processes?

Answer 24

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

Question 25

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 _____.

Answer 25

Contractile diaphragm

Ciliary body

Posterior pigmented epithelium

Question 26

What are the ten layers of the retina from superficial to deep?

Answer 26

1. Retinal pigmented epithelium
2. Rod and cones
3. Outer limiting membrane
4. Outer nuclear layer
5. Outer plexiform layer
6. Inner nuclear layer
7. Inner plexiform layer
8. Ganglion layer
9. Layer of optic nerve fibers
10. Inner limiting membrane

Question 27

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?

Answer 27

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

Question 28

Where is the organ of corti?

____ is the inner spiraling bony shelf serving as support for tectorial membrane and spiral ganglia

Answer 28

Floor of scala media resting on basilar membrane

Outer spiral lamina

Question 29

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 _____.

Answer 29

Saccule and utricle

Otolithic membrane

Linear acceleration