Exam III - Ocular Aging

Apoptosis

programmed cell death naturally occurring in cells. Cell becomes smaller and DNA becomes fragmented. Occurs by a series of cascade mechanisms involving caspases.

FasL

signal that binds to a receptor on a cell destined for apoptosis

Fas

receptor for FasL, the death signal in the process of apoptosis.

FADD (fast associated death domain)

this protein associates with the death domain of the Fas receptor in response to binding of the FasL death signal in the process of apoptosis.

Procaspase 8

this protein is activated via the fast associated death domain resulting in a cascade of caspase activation to perform apoptosis.

Bid

protein acting on mitochondria in response to caspase activity during apoptosis. This triggers the release of cytochrome C.

Bax

protein that promotes apoptosis via activation of Bid

Bcl

protein that inhibits apoptosis via inhibition of Bid

Cytochrome C

compound released by mitochondria at the end of the caspase cascade triggered by apoptosis. The final signal for programmed cell death.

Proteolytic enzymes

enzymes activated by caspases that degrade key cell proteins and genomic DNA via hydrolysis.

Apoptotic bodies

small fragments of the cell produced by apoptosis. Are further phagocytized by other cells

Necrosis

processes by which a cell dies prematurely by the loss of its membrane via the formation of blebs.

liquified

Vitreous becomes _____ with age. Collagen and hyaluronic acid dissociate. This causes contraction on the retina increasing the risk of retinal detachment. This is a normal process of aging.

collagens II and IX

Vitreal gel's ability depends on the interaction of these two collagen types

Collagen type IX

the gag component of the vitreous that serves as a molecular spring between collagen fibers.

Opticin

protein in the vitreous that attaches to collagen and prevents the collagen fibers from aggregating

Hyaluronan

gag of the vitreous that is not necessary for gel formation, but is required for the stabilization of collagen fibrils.

Retinal detachment

detachment of the neurosensory retina from the RPE. Increased risk with age when the vitreous becomes more liquified and aggregation of collagen fibers pulls on the retina.

cell destruction

breakdown of collagen

removal of gags from proteoglycans

three effects of alkali burns on the cornea

opacification

Alkali burns and their effects result in _____ of the cornea

Polymorphonuclear cells

inflammatory cells that migrate to the cornea due to chemotactic attraction to collagen peptide remnants occurring after alkali burns.

Matrix metalloproteinases

a group of enzymes that destroy collagen fibers after alkali burns of the cornea. Increase the development of ulceration and scarring of the cornea. Levels of these enzymes can be reduced by inhibitors of these enzymes such as TIMP and SIMP to reduce permanent damage to the cornea after an alkali burn.