Flashcards in Corneal Repair Deck (40):
What are the roles of corneal integrins?
-facilitates interactions between cells and extracelluar matrix
-impact cell adhesion and formation of junctions
-senses changes in the extracelluar environment
-communicated to the cell nucleus by an alteration in the cytoskeleton
What are cytokines?
They are released in health and damaged corneas
What are the 2 roles of cytokines?
-communicates between cells and surrounding tissues
-controls the growth of corneal cells
What are the 3 roles of growth factors?
-promotes proliferation of corneal cells
-induces migration of cells
-maintains corneal transparency
What are the 3 wound healing biomolecules?
In which epithelial layer can cells divide?
Basal (through mitosis)
Name the 3 epithelial layers?
And how thick are they?
-basal layer: 1 cell thick
-surface layer: 2
What is the process of epithelial replacement
Stem cells in the peripheral cornea divide-->new cells move toward the center to become basal cells-->BC move up and become wing cells-->WC move up and become surface cells-->SC shed into tear film-->turn over in 7 days
When there's a corneal injury what happens to mitosis?
What's released if the cornea is damaged?
Growth factors and cytokines
The process of wound healing
-growth factors and cytokines are released
-hemidesmosomes dissemble along the wound edge
-this changes the cytoskeleton which causes cells to migrate and cover the wound
-you get adhesion molecules
---epithelial sheet adheres to basement membrane
-the defect is covered by a single layer of cells and junctions are formed between the neighboring cell
-mitosis resumes and normal cell density is reached
-hemidesmosomes replace biochemical bonds holding basal cells
Cell migration requires control of what 3 things
And what do these preserve
The structural integrity of epithelial sheet
How long does it take small lesions of the epithelium to heal?
How long does it take if the basement membrane of the epithelium is damaged?
Several months for normal hemidesmosomes
T/F: the epithelium is usually scar free
During recurrent corneal erosion the corneal epithelium sloughs off either ___ or ___
Continually or periodically
What are the 2 causes of recurrent corneal erosion?
-Poor adhesion between Epithelium and Basement Membrane
-Poor adhesion between Basement Membrane and underlying tissue (stroma)
Recurrent corneal erosion occurs....
-after incomplete healing of an abrasion (hemidesmosomes malformed) OR
by epithelial basement membrane dystrophy
If someone comes in every few months and says that they have pain and irritation or have it all the time, and you put fluorescein and see spots on the cornea what could this be?
Recurrent corneal erosion
What are the treatments of recurrent corneal erosion?
-anterior stromal micropuncture
-superficial karate to your (removal of epithelium)
Is bowmans layer cellular or acellular?
Bowmans layer is composed primarily of ___
T/F: BL's is highly resistant to pentration or damage
T/F: Bowmans layer does not regenerate
What replaces the bowmans layer when damaged?
Stroma scar tissue or epithelium
Bowmans layer is ___ to the epithelium
The stroma is composed of?
-extracelluar ground substances
When the stroma is injured what occurs?
Keratocytes increase in number; some stimulated to become myofibroblasts--> cause wound bed to contract--> wound coverage by epithelium over defect
Regenerated stromal collagen is ____ than the original fibrils and alignment and organization are not as ____ -> ______ probability of scarring
After healing of the stroma is complete what happens to the myofibroblasts
They undergo apoptosis or revert back to keratocytes
How long does it take the stroma to heal?
The basement membrane of the endothelium
T/F: descemets membrane remains the same throughout life
False. It thickens
Descemets membrane is composed of ___
When DM is injured, its regenerated by what?
Stroma keratocytes and the endothelium
The single layer of flattened cells that is the most posterior part of the cornea
What are the shape of the endothelium cells?
The basal part of the endothelium rests on the ____ and the apical surface lines the ___
T/F: there is little mitosis that occurs in the endothelium