Exam 4: Eye Flashcards
What is the term for the eyeball?
bulbus oculi
What are the 3 tunics of the eyeball? (outer –> inner)
fibrous tunic
vascular tunic
internal tunic
What 3 structures made up the fibrous tunic of the eyeball?
Sclera
Cornea
Cornea Limbus
The cornea is (vascular/avascular). Why?
avascular
need clarity for vision!
What are the 5 layers of the cornea?
- Anterior epithelium (corneal)
- Anterior limiting membrane
- Substantia propria
- Posterior limiting membrane
- Posterior epithelium (corneal)
What tissue type is the anterior epithelium of the cornea (corneal epithelium) made of?
nonkeratinized stratified squamous
+ free nerve endings
What disease occurs with damage to the anterior epithelium of the cornea?
corneal ulcer
What covers the anterior epithelium of the cornea?
tear film produced by serous/mucous glands
What is the anterior limiting membrane of the cornea considered?
basement membrane of corneal epithelium
What is another name for the substantia propria?
stroma
What tissue type is the substantia propria made of in the cornea and what is unique about it?
DICCT but fibers are within same orientation within each layer (but differ between layers)
________ (type of cells) are present in the stroma/substantia propria.
Keratocytes
Function of keratocytes
maintain proper hydration to maintain clarity
What is another name for the Posterior Limiting Membrane of the cornea?
Descement’s Membrane
What is the posterior limiting membrane of the cornea considered to be?
basement membrane of substantia propria
What kind of fibers are present in the posterior limiting membrane?
collagen
What kind of cells produce the posterior limiting membrane?
posterior epithelial cells
What is a descemetocele?
when fluid pushes out on posterior limiting membrane and eye is close to perforating
What tissue type makes up the posterior epithelium of the cornea?
simple squamous –> low simple cuboidal
Posterior epithelium has cells that contain numerous _____.
mitochondria
What is the function of the posterior epithelium of the cornea?
maintain corneal transparency
What tissue type makes up the Sclera? Fiber orientation?
DICCT (transverse/oblique fibers between longitudinal fibers)
What two layers are on top of the Sclera?
Bulbar sheath
Bulbar conjunctiva
the bulbar sheath that covers the Sclera is made of ______.
fascia
What is another name for Bulbar Sheath?
Tenon’s Capsule
Which layer of the Sclera is the outermost?
Bulbar conjunctiva
What is the area cribrosa?
area of sclera perforated by CN II axons that pass through to form Optic N
What is the Cornea Limbus?
corneoscleral junction (between cornea + sclera)
What is another name for the vascular tunic of the eyeball?
uvea
What are the 3 parts of the vascular tunic of the eyeball?
choroid
ciliary body
iris
4 parts/layers of the choroid
vascular layer
tapetum lucidum
choriocapillary layer
basal complex (Bruch’s membrane)
What is the function of the Tapetum Lucidum?
reflects light back that passes through retina to maximize light perception in low light
Which domestic animal does not have a Tapetum Lucidum?
pig
Choriocapillary layer
layer of capillaries right next to retina
Basal complex (Bruch’s membrane)
thick basement membrane between capillaries in choroid
What kind of cells are present in the Basal complex?
pigment epithelial cells
Function of Basal complex
acts as “blood-brain barrier” to protect eye and maintain function
Ruminants and horses have a _____ tapetum.
fibrous
The posterior surface of the ciliary body is covered by 2 layers of epithelial cells called:
pars ciliaris retinae
Where does the ciliary body begin?
ora serrata (serrated edge)
Ciliary processes from the Ciliary Body project into the posterior chamber and produce:
aqueous humor
Where the zonular fibers attach?
ciliary processes
What is the function of zonular fibers?
suspend the lens
What is the function of the ciliary muscle?
contraction –> less tension on lens –> more convex (rounded) and focuses light differently onto retina
Accommodation
lens changes to where detail is perceived the best
Where do the anterior and posterior chambers of the eye communicate?
the pupil
What two muscles are present in the iris? SNS or PSNS control?
Sphincter - PSNS
Dilator pupillae - SNS
What separates the anterior chamber from posterior chamber of the eye?
iris
Stroma of the iris is (vascular/avascular) and many _____ (cell type).
vascular
melanocytes
What are the 2 layers of iris epithelium called?
pars iridica retinae
Iridic granules (= corpora nigra) + function
projections on iris
function: protects retina when sun at low levels in sky
Iridocorneal angle
where aqueous humor drains from eye
What causes glaucoma?
failure to drain aqueous humor from iridocorneal angle
Pectinate ligament
has “Spaces of Fontana” where aqueous humor drains to scleral venous system
What is another name for the internal tunic of the eyeball?
retina
What is the blind part of the retina called? What 2 things make it up?
pars ceca retinae =
pars ciliaris retinae + pars iridica retinae
Where does the Pars Optica Retinae layer of the Internal Tunic begin?
ora serrata (serrated edge) point that separates blind vs. optic part of retina
______ epithelium is present in the Pars Optica Retinae of the Internal Tunic of the eye
retinal pigment epithelium
What are considered first order neurons (in the internal tunic)?
rods + cones (photoreceptors)
What are considered second order neurons?
bipolar neurons
What are considered third order neurons?
ganglion cells
Other than 1st - 3rd order neurons, what 3 cell types are in the Pars Optica Retinae of the Internal Tunic?
radial glial (muller) cells
horizontal cells
amacrine cells
Function of radial glial (muller) cells
connect peripherally + centrally to outer and inner limiting membranes by adhering junction (tight barrier for cell support)
Where are horizontal and amacrine cells located?
inner nuclear layer
Function of horizontal + amacrine cells
interneurons that regulate action potentials (through order neurons)
________ is present in the Retinal Pigment Epithelium except over the Tapetum Lucidum.
melanin
What is the function of melanin in the retinal pigment epithelium?
transport nutrients, block stray light
phagocytize old rods/cones after waking up
What is the area for the most acute vision (more cones, fewer vessels)?
Area centralis retina
The lens is between the ____ and the ____.
iris and the vitreous body
The lens is (biconvex/biconcave).
biconvex
Two parts of the lens
capsule + lens epithelium
What tissue type is the lens epithelium?
simple cuboidal epithelium
What is Nuclear Sclerosis?
where the lens becomes cloudy with age but no effect on functional vision
What is the visual pigment in Rods?
Rhodopsin
Rods are better for (bright/dim) light vision and cones are better for (bright/dim) light vision.
dim
light
Axons of ______ form CN II (Optic N).
ganglion cells
Lens epithelium differentiates into lens fibers at ________.
lens equator
Any area of lens opacity =
cataract
Zonular fibers are similar to _____ fibers.
elastic
What make up the components of the vitreous body?
99% water
1% hyaluronic acid
collagen fibrils
Adnexa
structures that surround the eye (glands, eyelids)
What tissue type is the adnexa of the eye made of?
thin keratinized stratified squamous (+ apocrine, sebaceous glands, hair follicles)
What is another term for eyelashes?
cilia
What is the inner surface of the adnexa called?
palpebral conjunctiva
What tissue type makes up the palpebral conjunctiva?
non-keratinized stratified squamous epithelium + goblet cells (rested on CT)
What kind of glands are present in the margin of the eyelid?
tarsal (meibomian) glands
What is the tarsal plate?
plate of collagen that embeds/stiffens tarsal gland (so act like “windshield”)
What is ectropion?
dysfunction of tarsal plate (= drooping eyelids)
What is another name for the third eyelid?
nictitating membrane
Third eyelid is covered by ______ and has a core of _____.
conjunctiva
elastic
What kind of gland is present in the nicitating membrane?
superficial gland of the third eyelid
What is Cherry Eye?
inflammation of the superficial gland of the third eyelid where palpebra conjunctiva is pushed out
List the 10 layers of the retina (outer –> inner)
Retinal Pigment Epithelium
Layer of Rods + Cones
External Limiting Membrane
Outer Nuclear Layer
Outer Plexiform Layer
Inner Nuclear Layer
Inner Plexiform Layer
Ganglion Cell Layer
Optic Nerve Fiber Layer
Internal Limiting Membrane
What is present in the Retinal Pigment Epithelium of the Retina? Function?
supportive cells
physical/nutritional support to rods/cones
What is present in the Layer of Rods + Cones of Retina?
outer and inner segments of rods + cones
What is present in the Outer Nuclear Layer of the Retina?
nuclei of rods + cones
What is present in the Outer Plexiform Layer of the Retina?
synapse of rods/cones & bipolar neurons
What is present in the Inner Nuclear Layer of the Retina?
mainly nuclei of bipolar neurons, amacrine cells, horizontal cells
What is present in the Inner Plexiform Layer of the Retina?
axons of bipolar cells synapse on dendrites of ganglion cells
What is present in the Ganglion Cell Layer of the Retina?
a few cell bodies of ganglion cells
What is present in the Optic Nerve Fiber Layer of the Retina?
axons from ganglion cells
What is present in the Internal Limiting Membrane of the Retina?
one end of radial glial/Mueller cell processes
What is the function of the Internal Limiting Membrane of the Retina?
retina stabilization