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122 Cards in this Set
- Front
- Back
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what does the visual axis intersect?
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cornea
anterior chamber lens vitreous body fovea |
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what does the cornea do?
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gathers light; directs it into interior of eye
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where is iris?
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On post part of ant chamber
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what is the path of fluid flowing?
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Fluid flows from posterior chamber thru pupil and into anterior chamber
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what does the ciliary body do?
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-changes thickness of lens
-Puts tension on lens and tether it |
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what are the 3 layers of the wall of the eye?
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fibrous tunic/ outermost
uvea= vascular tunic (tunica vasculosa)/ middle retina- innermost layer |
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what are the parts of the fibrous tunic?
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cornea
sclera |
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what maintains continuity w/ the conjuctiva?
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fibrous tunic
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what are the parts of the uvea?
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iris
ciliary body choroid |
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what part of the eye is highly vascular?
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choroid
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what are the parts of the retina?
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-retinal pigment epithelium
-neural photoreceptor cells (rods and cones) -neuronal integrative circuitry and supporting cells |
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where is the cornea in the fibrous tunic?
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anterior part of fibrous tunic
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what's interior surface of cornea lined by?
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simple endothelium
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describe the sclera:
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dense collagenous conn tissue sheath
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how do part of fibrous tunic interact?
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cornea is in continuity w/ sclera
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what is the limbus?
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-junction b/w cornea and sclera
-marks continuity b/w epithelium that lines surface of cornea and epithelium that lines conjunctiva |
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describe the cornea:
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transparent
avascular -directs light to lens -has 2x refractive power of lens |
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where do you have vessels near cornea?
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limbus
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are cornea basement membranes typical basement membranes?
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no
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what are the layers of the cornea?
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epithelium
Bowman's membrane or layer stroma Descemet's membrane endothelium |
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what part of the cornea borders anterior chamber?
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endothelium
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what does the shape of cornea determine?
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refractive power
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what does lasik surgically reshape for better vision?
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cornea!
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what does cornea get nutrients from?
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limbus
aqueous humor in ant chamber |
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describe epithelium on cornea:
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stratified squamous epithelium
non-keratinizing highly proliferative bathed by tears from lacrimal gland abundant pain afferents somewhat fluid permeable barrier |
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is stroma of cornea thin or thick?
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thick
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how are wounds of corneal epithelium repaired?
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mitosis and migration of stem cells located in basal layer at lateral margins (limbus)
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describe stroma of cornea:
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-substantia propria
-multilayered -collagen I fibers, some collagen V (non-fibrillar) -50-60 layers of keratocytes -alternating layers of fibrocytes & ECM fibers & proteoglycans -orientation of collagen fibers changes layer to layer |
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are nerve fibers in cornea unmyelinated or myelinated?
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myelinated in stroma
as fibers go thru bowman's layer, become unmyelinated |
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what part of cornea is involved in fluid transport?
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Corneal endothelium (and epithelium) are involved in fluid transport
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what's the purpose of fluid transport in cornea?
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• keeps stroma relatively dehydrated
• contributes to transparency of cornea |
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describe cornea endothelium:
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-leaky intercellular juncs
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what purpose does the cornea's endothelium serve by being leaky?
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fluid exchange b/w stroma & anterior chamber
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does the transparency of descemet's membrane remain constant?
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changes with age and contributes to decreased light transmission
aahh! |
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describe the limbus:
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-outflow path for aqueous humor
-trabecular meshwork -canal of Schlemm |
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what happens if cornea is too hydrated?
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not transparent
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what's the choroid?
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part of the uvea
highly pigmented- has melanocytes highly vascular |
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where's the choroid?
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in b/w the sclera & retina
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how is the vessel layer of choroid linked to sclera?
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collagen and elastin fibrils
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what are the layers of the choroid?
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vessel layer
choriocapillary layer Bruch's membrane |
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what's the choriocapillary layer?
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-part of choroid
-vascular supply for retina: rods, cones, pigmented retina |
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what's Bruch's membrane?
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-part of choroid
-separates choroid from retinal pigment epithelium |
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what part of choroid has melanocytes?
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vessel layer
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what's the ciliary body?
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-part of uvea
-thickened part of vascular tunic at level of lens |
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how does the shape of lens change for accommodation?
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ciliary muscle!
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what are ciliary zonules?
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-ciliary body ligaments
-project to lens capsule -oxytalin fibers running from BM of non-pigmented ciliary epith to BM of lens epith (lens capsule) |
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what type of epithelium on ciliary processes?
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double layer!
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what happens when you're trying to look at something in the distance?
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ciliary muscle relax
zonules tense lens is flattened |
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what happens when your'e trying to look at something up close?
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ciliary muscle tenses
zonules relax lens rounds up/bulges |
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where does aqueous humor come from?
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epithelial apparatus of ciliary processes!
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describe ciliary processes:
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-highly vascular
-project into posterior chamber |
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describe aqueous humor?
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-ion composition similar to plasma
-contains glucose but very little protein -nutrition to lens -maintains intraocular pressure |
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list ciliary processes parts:
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epithelium
deep layer/outer layer surface layer |
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describe epithelium of ciliary processes:
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2 layers aligned apex to apex
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describe deep layer/outer layer of ciliary processes?
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-heavily pigmented
-continuous w/ retinal pigment epithelium |
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describe surface layer of ciliary processes?
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-fluid transporting cells
-apical surface faces pigment epithelium -highly folded basolateral membrane borders posterior chamber |
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describe blood-aqueous barrier:
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occluding juncs @ apex of surface epithelium
-tight juncs at apical margin b/w adjacent cells of fluid transporting epithelium -Tight juncs that are closer to ciliary channel than desmosomes occluding juncs = tight juncs |
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what causes glaucoma?
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-obstruction to outflow & drainage of aqueous humor
-elevated intraocular pressure leads to tissue degeneration thruout eye b/c inc pressure impact/impinging on vascular supply on choroid --> ischemic events |
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what is significance of ciliary channel?
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-separates pigmented ciliary epithelial cells and non-pigmented ciliary epithelial cells
-apical domains of these cells face ea other- unique!! |
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what does the basal lamina of the nonpigmented ciliary epithelial cell border?
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posterior chamber
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what's abundant on basal lamina of nonpigmented ciliary epithelial cell?
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Lots of Na/K /ATPase on basal lamina of surface cell
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what's the importance of the pigmented ciliary epithelial cell/Deep layer of epithelium?
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-generates fluid that originates in fenestrated capillary
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what's the main func of the iris?
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regulates pupillary diameter
(the amount of space you can see puppies w/) |
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list parts of iris:
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-conn tissue core on post surface , which borders posterior chamber, is lined by heavily pigmented epithelium
-anterior surface -stroma |
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what's the dilator muscle of the pupil?
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pigmented myoepithelium of iris
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what's the constrictor muscle of pupil?
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stroma of iris
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what's the importance of the pigmented ciliary epithelial cell/Deep layer of epithelium?
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-generates fluid that originates in fenestrated capillary
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what's the main func of the iris?
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regulates pupillary diameter
(the amount of space you can see puppies w/) |
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describe iris:
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-conn tissue core on post surface , which borders posterior chamber, is lined by heavily pigmented epithelium
-anterior surface -stroma |
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what's the dilator muscle of the pupil?
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pigmented myoepithelium of iris
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what's the constrictor muscle of pupil?
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stroma of iris
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what are the parts of the posterior surface of iris?
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pigmented epithelium
pigmented myoepithelium |
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describe the pigment epithelium of the iris?
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continuous w/ the pigment epithelium of the ciliary body
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which pupil muscle is under sympathetic control?
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dilator muscle of pupil
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which pupil muscle is under parasympathetic contol?
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constrictor muscle of pupil
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describe the iris stroma:
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highly vascular
fibroblastic conn tissue has melanocytes- determines eye color constrictor muscle of pupil |
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what's eye color determined by?
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quantity and distribution of pigment cells
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how do you get blue eyes?
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few melanocytes
little pigment in stroma |
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how do you get grey to green eyes?
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moderate amt of melanocyte pigment
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how do you get brown eyes?
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HEAVILY pigmented melanocytes in stroma
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how do you get pink eyes?
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albinism
absence of melanocytes |
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what's eye color determined by?
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quantity and distribution of pigment cells
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how do you get blue eyes?
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few melanocytes
little pigment in stroma |
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how do you get grey to green eyes?
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moderate amt of melanocyte pigment
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how do you get brown eyes?
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HEAVILY pigmented melanocytes in stroma
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how do you get pink eyes?
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albinism
absence of pigment |
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describe lens of eye
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biconvex
transparent avascular |
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what are the parts of the lens?
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-capsule
-lens epithelium -lens fibers |
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what's the lens capsule
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a basement membrane
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describe the lens epithelium:
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-simple cuboidal epithelium
-only on ANTERIOR surface of lens -devoid of occluding juncs |
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describe lens fibers:
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-elongated (7-10mm)
-highly differentiated cells -oriented anterior --> posterior (spans depth of lens) -has high content of crystallins (90% of protein content of cell) |
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where do lens fibers originate?
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germinal zone @ periphery of lens
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what is purpose of crystallins?
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increase refractive index of lens
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where's the highest crystallin content?
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lens fibers near center of lens
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what is mitotic in lens? where?
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-Ant. Cuboidal epithelium lens fibers
-only at periphery/ margin of lens: germinal |
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what happens in cataracts?
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lens fibers become progressively opaque
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what happens in presbyopia?
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-loss of elasticity of lens with age
-inability to accommodate for near vision |
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what are the 2 main layers of the retina?
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pigment epithelium (outermost)
neural/photoreceptor retina (inner layer) |
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describe pigment epithelium of retina:
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simple cuboidal
ion/fluid transporting epithelium rests on Bruch's membrane (adjacent to choriocapillary layer) -apical membrane contacts photoreceptor outer segments |
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what are the 4 main funcs of the pigment epithelium?
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1) makes fluid to nurture rods and cones
-Na/K/ATPase on apical membrane 2) makes melanin 3) phagocytoses photoreceptor discs shed by rods 4) pools Vitamin A used in regeneration of rhodopsin by rods |
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what's purpose of melanin?
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absorbs light
limits reflection and scatter |
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what does pigment epithelium do w/ Vitamin A?
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-pools Vitamin A used in regeneration of rhodopsin by rods
-esterifies Vit A to provide substrate for rhodopsin synthesis |
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what's the site of retinal detachment?
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interface between photoreceptor cells and the pigmented epithelium b/c it's weak
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what are the parts of the neural retina?
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photoreceptors (rods & cones)- sensory neurons
supporting cells integrative neurons |
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what are the parts of rods and cones?
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synaptic body
inner segment outer segment |
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describe synaptic body of rods and cones:
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synaptic contact w/ bipolar cells of retina
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describe the outer segment of the rods and cones:
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photosensitive receptor apparatus
highly modified cilium contacts pigmented epithelium |
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what's the func of rods?
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night vision (scotopic)
low acuity |
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what's the photopigment of rods?
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rhodopsin
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what's the distribution of rods?
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peripheral
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how many rods are there?
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120 million
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what's the func of cones?
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daylight (photopic)
color high acuity |
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what's the photopigment of cones?
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3 pigments
wavelength specific |
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what's the distribution of cones?
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central
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how many cones are there?
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6 million
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what's ora serrata?
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anterior margin of neural retina
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what's in the fovea?
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cones only
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what's the fovea?
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area of highest visual acuity at center of visual axis
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what's the optic disc?
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blind spot
no photoreceptors -coalescence of ganglion cell processes forming optic nerve |
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what's the thinnest region of eye?
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fovea centralis
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what happens when neural retina ends?
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Neural retina ends, but pigmented epithelium continues anteriorly
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describe the inner segment of rods and cones:
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perinuclear region
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