The Eye Flashcards
The fibrous tunic of the eye is ____ and ____
Sclera (tunica fibrosa)
Cornea
The Vascular tunic is what three things
Choroid, Ciliary body, Iris
The inner tunic is what
Retina
The fovea centralis
point where you have the sharpest visual acuity
What part of the fibrous tunic is transparent
The cornea
What part of the fibrous tunic is opaque
Sclera
The sclera is lined by the
middle or vascular pigmented layer that absorbs light
What is the limbus
the zone of transition of the epithelium of the conjunctiva with that of the cornea. it is also the boundary of the transparent cornea with the opaque sclera
What are the functions of the corneoscleral coat
- Protects the inner structures of the eye
- Together with the intramural fluid pressure, it maintains the shape and consistency of the eyeball
What are the two layers of the Sclera
Episcleral layer and Sclera proper
What is the outer layer of the sclera
Episcleral layer
What is the structure of the episcleral layer
loosely arranged collagen and elastic fibers
highly vascularized
The episcleral layer attaches
the lining of the eyelid (conjunctiva) to the sclera
What is the strucuture of the Sclera proper
Made up of interlacing collagen fibers
The Sclera proper is the attachment site for
tendons of extrinsic eye muscles
Collagen bundles of the sclera proper are alway aligned _____ to outer surface of sclera
Parallel
What is the lamina cribrosa of the eye
perforated disc of the sclera
The Lamina cribrosa provide a passthrough for
The optic nerve fibers
Anteriorly the sclera is continuous with
the cornea
The junction between the two scleral layers is
the limbus (it is highly vascularized)
Posteriorly the sclera is continuous with the
dual covering of the optic nerve
How many layers does the cornea have
5
What are the five layers of the cornea
Corneal epithelium Bowman's membrane Corneal Stroma Descemet's membrane Corneal endothelium
The corneal epithelium is what kind of epithelium and how many layers
5-6 layers of stratified, nonkeratinized squamous epithelium
The corneal epithelium has high ____ activity in the basal layer
mitotic
What is the turnover rate for the corneal epithelium
1 week
What is bowman’s membrane
Acellular layer separates the corneal epithelium from stroma
Boman’s membrane structure
randomly arranged collagen fibers
What is the structure/compositions of corneal stroma
Thin layers of ordered arrays of collagen fibers
What is the structure/composition of Descemet’s membrane
Acellular layer of collagen bundles
Separates storm from endothelium
Descemet’s membrane
Single layer of large squamous cells in in the cornea
Corneal endothelium
The basal cells of the corneal epithelium are anchored to Bowman’s layer by
hemidesmosomes
Corneal endothelium contain abundant mitochondria, why?
They participate in the active transport of material form aqueous humor into descemet’s membrane and part of the corneal stroma
_____ nerves can be found in the storm. After crossing Bowman’s layer nerves become ________ and extend toward the surface in the intercellular spaces of the corneal epithelium
myelinated, unmyelinated
are blood vessels present in the stroma
No
The stroma of the cornea is formed by collagen lamellae oriented at
an angle to one another
The choroid extend anterior to
ora serrate of the retina
The choroid is _____ vascularized with _____ CT
highly , loose CT
Contains small blood vessels that supply cells of the retina
Choriocapillary network
Choroid forms the ________ network
choriocapillary
The loose CT of the Choroid functions
Highly vascularized
forms choriocapillary network
provides nutrients to outer layers of the retina
consists of medium and large arteries and veins as well as a widebore capillary network
Contains melanocytes
What is brush’s (glassy) membrane
Acellular fused basal laminae of choriocapillaris and pigmented retinal epithelium
Bruch’s membrane is formed by
The basal lamina of the pigmented epithelium
Subjacent layers of collagenous and elastic fibers
The basal lamina of endothelial cells of the underlying capillary network (choriocapillaris)
Wedge-shaped expansion of choroid peripheral to the lens
Ciliary body
The ciliary body is covered by
a double layer of cells
The innermost layer of ciliary body is continuous with
the pigmented layer of the retina
The surface/outer layer of the ciliary body is from the
sensory layer of the retina
Where is aqueous humor produced
in the endothelial layer of ciliary body
______extend to just behind lens equator and anchor the lens in place
suspensory ligaments (of Zinn)
Where are the suspensory ligaments (of Zinn) located
in the ciliary body
Ciliary muscles structure and function
smooth muscle mass that changes the shape of the lens
innervated by parasympathetic neurons
What part of the eye are the ciliary muscles located
in the Ciliary body, which is part of the Vascular tunic (urea)
The iris has how many surfaces
two
The anterior surface of the iris lacks
epithelial lining
The posterior surface of the iris is lined by
dual layer of pigmented epithelial cells, a direct continuation of the pigmented layer of the retina
The sphincter pupillae
Consisting of smooth muscle cells
has acetylcholine receptors and is innervated by parasympathetic nerve fibers
contraction constricts pupil (miosis)
Dilator pupillae
consisting of myoepithelial cells
contains alpha adrenergic receptors and is innervated by sympathetic nerve fibers
- contraction of the dilator causes pupil dilation (mydriasis)
What are the 3 components of aqueous humor
H20, Na+, Cl-
The aqueous humor is produced by
ciliary epithelium lining the ciliary processes
______ is a modified annular vessel forming a complete circle at the apex of the anterior chamber angle (corneal-irideal angle)
Canal of Schlemm
The obstruction in the drainage of aqueous humor leads to an increase in intraocular pressure that gradually damages the retina and causes blindness if untreated. This condition is called ___
glaucoma
What is the major escape route of the aqueous humor
The canal of Sclemm.
What are the two groups of ciliary muscles responsible for
one group of muscles is responsible for flattening the lens
A second group of muscles is responsible for allowing the lens to become thicker
The nonpigmented suface layer of cells in the ciliary body secrete aqueous humor where
into the posterior chamber
The non pigmented surface layer of cells in a ciliary body have _____ infoldings
basal
Aquesous humor percolates through
Travecular network and flows into canal of Schlemm
Where is the iris located
anterior to the lens and separates the anterior and posterior chambers
The Iris surrounds the
Pupil
The angle of the iris is formed at
lateral borders of the anterior chamber
The iris angle is composed of
loose CT
The angle of the iris is part of the passageway for
aqueous humor
The iris has how many layers of epithelium
2
The inner layer of the iris is composed of
pigmented epithelial cells
The outer layer of the iris is composed of
radially oriented myofilaments (dilate) and concentric layer of myofilaments (constrict)
The more melanocytes present in the iris the
darker the iris
What are the two subdivision of the retina
The photosensitive region, which lies posterior to the ora serrata
The nonphotosensitive region which lies anterior to the ora serrata
What is the optic disc
region on posterior aspect of the eye where optic nerve exits
has no photosensitive retina and constitutes the blind spot
what is the location of the fovea centralis
2.5 mm lateral to optic disc (note that the optic disc is posterior to the ora serrata and is on the posterior aspect of the eye where the optic nerve exits)
The fovea centralis contains ______ pigment
yellow
What is the macula lutea
The yellow pigment at the fovea centralis
The fovea centralis contains what type (s) of photoreceptors
only cone-type
What is the area of most acute vision
The fovea centralis
The nonphotosensitive region of the retina, which lies anterior to the ora serrata consists of ____ cell layers covering, iris, ciliary body and ciliary processes
two cell layers
The anterior chamber is posterior to _____ and anterior to ____
cornea, and anterior to iris
what is posterior to the cornea and anterior to the iris
The anterior chamber
what is posterior to iris and anterior to lens
Posterior chamber
What is the chamber posterior to the lens
The vitreal chamber
What chamber contains the vitreous body
vitreal chamber
In the vireal chamber what is the site of a fetal artery
the hyaloid canal
The hyaloid canal is the site of what
a fetal artery
The vitreous body is a _____ mass composed of
gelatinous mass composed of 99% water, hyaluronic acid, and vitrein
What is glaucoma
increased intraocular pressure due to compromised drainage of aqueous humor from anterior chamber