Limbus and Uvea Flashcards
What are the three functions of the limbus?
- Nourish peripheral cornea
- Outflow for aqueous humor
- Corneal epithelium regeneration
How does the aqueous flow into venous blood?
- Canal of Schlemm
2. Uveoscleral Outflow (Vortex Veins)
How many collector channels drain into Schlemm’s canal?
25-35
What are the three main properties of the Uvea?
- Highly vascular
- Richly innervated
- Regional specialization
What are the three ciliary body functions? (Triple A)
- Aqueous Humor Formation
- Accommodation
- Absorption of Light
What are the functions of the Iris?
- Illumination control
- Aperture control for focus
- Aberration control
as the cornea transitions into the sclera some of the layers in the cornea disappear while others continue on into the sclera
modified corneal layers
at the limbus there is modification of the endothelium to produce…
hint: the aqueous fluid drains through this
trabelcular meshwork
a blockage in the meshwork would prevent adequate aqueous outflow and result in an increased IOP and result in…
glaucoma
after passing through the trabecular meshwork, aqueous is transported into the…
schlemm’s canal
stem cells play a major role in maintaining the transparency of the cornea as a result of….
regeneration of epithelial cells
the region that lies anteror to the lens, between the iris and the endothelium of the cornea
anterior chamber
the region that surrounds the lens btwn the ant surface of the vitreous and the post surface of the iris
posterior chamber
the region between the iris and the corneal endothelium that is line w/ the trabecular meshwork
the angle
the boundary btwn the cornea and the sclera. extends through the depth of the cornea
corneal scleral limbus
the limbus is supplied by the….
ant ciliary artery and long post ciliary artery
stem cell division increases with _______ stress
corneal
loss of _______ leads to permanent damage to limbal and corneal epithelium
limbal epithelium
which nerves carry the nerves at the limbus
long and short ciliary nerves
what branch of CN are the nerves at the limbus branches of
ophthalmic division of CN 5
the nerves at the limbus travel through ______ and the ______ aspect of the ciliary body
suprachoroid
superior
the nerves at the limbus traverse approx ____ of the cornea
2/3
the nerves form two branches: one in the _____ which is the most dense, and one in the _____
epithelium
stroma
which cell layer are the epithelial nerves found
basal cell layer but some single branches extend to the squamous cell layer
when do the nerves at the limbus lose myelin sheath
about 1.5mm entry into the cornea
the stem cells at the limbus are … (3 things)
- basal cell layer
- daughter cells (transient amplifying cells)
3 form basal ep cells
- daughter cells migrate from basal epithelial cells to _______
- cells move from ______ to cornea
- _____ of surface cells
this is called the _________ of renewal
- surface epithelium
- conjunctiva
- desquamation
xyz method
changes in the epithelium at the limbus
- becomes ______
- less _____
- incrase in ____ cells
- _______ are smaller and more dense
- _____ becomes undulating
- LESS _____
- thicker
- uniform
- wing
- basal cells
- basement membrane
- transparent
changes in bowman’s membrane at the limbus
- stops at ______
- demarcates limit of _____-
- peripheral cornea
2. anterior cornea
nerves that pass from stroma to epithelium
ramus perforans
changes in the stroma at the limbus
- corneal stroma is continuous w/ ______
- loses regularity of ______
- variation in _______ spacing
- increasing variation in _______
- LESS ______
- scleral stroma
- lamellae
- fiber
- fiber diamter
- transparency
changes in descemet’s membrane at limbus
- _______ in the limbus or sclera
- extremem limit of descemet’s membrane is marked by a ring called ______
- not found
2. “schwalbe’s ring”
changes in the endothelium at the limbus
- continues with _____
- forms the _______ layer and lines the _____
- ______ forms the trabecular meshwork
- _________: endothelial layer present in lumen of trabecular meshowrk (aggressive glaucoma)
- cornea
- trabecular endothelial layer
angle - modified endothelium
- chandler’s syndrome
a complete trabeuclar endothelial layer is found in ______ but not primates
rabbits
where is the canal of schlemm found
the corneoscleral junction
the canal of schlemm is an _______ channel
annular
how many mm in diameter is the canal of schlemm
0.3mm
what kind of cells line the canal of schlemm
endothelial cells
aqueous is drained into the canal of schlemm from the ______ via the ______
anterior chamber
trabecular meshwork
T or F: the canal of schlemm is a vein
fucking false motherfucker theres no fucking valves
a annular structure in the human eye, a protrusion of the sclera into the anterior chamber
scleral spur
the filtration angle has its apex at the ______, base at the _____, and attachment of the ______, and divided into ____ regions
schwalbe’s ring
scleral spur
ciliary muscles
3
the trabecular meshwork is divided up into 2 parts:
a uveal and corneosclearal part
the uveal:
- ____ meshwork
- forms ______
- _____ passages
- inner
- cords (in cross-section)
- wide
corneoscleral:
1. _____ part
2. _____ to uveal part
3. forms ______
4. numerous ______
5. resistance to _____
- largest
- external
- flattened sheets
- pores
- outflow
the greatest resistance to outflow is found in the …
trabecular meshowrk
the wall of canal of schlemm produces a resistance of ___ % of total ressistance
5%
the region separting the endothelial lining of the canal of schlemm and the corneoscleral meshwork is called the….
cribiform layer or the jutacanalicular tissue
the connection btwn canal of schlemm and ant chamber is called the…
canals of sondermann
there are no canals in the canal of sondermann, just ______. this incrases the _____ of the canal
spaces
surface area
aqueous flow into canal of schlemm
- canal is lined w/ ______ cells w/ ____ junctions
- _______transport aqueous into canal (main)
- what kind of transport
- _____ diffusion
- driven by _____ pressure gradient
- endothelial cells w/ tight junctions
- giant vacuoles
- active transport (v. small)
- passive diffusion (small)
- IOP pressure gradient
large vacuoles form on the _____ side of the endothelial cells that are called ____ vacuoles
basal
giant
the vacuoles burst on the _____ side emptying its contents into the canal of ____
apical
schlemm
the small amount of fluid moved by active transport via ______ is way fucking small compared to those big ass giant vacuoles
active transport
the path of aqueous outflow is through the
1. or 2.
- canal of schlemm
2 uveoscleral outflow (vortex veins)
wehre are the collector channels located on
external wall of schlemm’s canal
the collector channels empty into the _______ or the _____ veins and eventually flows into the ________ veins
deep scleral venous plexus
aqueous veins
episcleral veins
aqueous flow through the uveoscleral outflow
- passively drains _____ %
- ____ resistance
- _____ reduction w/ age
- prostaglandins reduce ______ (affect permeability w/in ciliary body)
- 5-35%
- no
- modest
- IOP
aqueous flow is derived from plasma in _______
ciliary body processes
aqueous flow flows around the ____ into the _____
lens
anterior chamber
aqueous flow passes out through the trabecular meshwork through the ___________ and _____
OR
into _____ tissue surround ciliary muscle
canal of schlemm and collector channels
OR
connective
aqueous flow returns to blood vessels via
1. or 2.
- aqueous veins/episcleral veins
2. choroidal vessels
