Lens Flashcards
What is the function of the lens?
Responsible for fine-tuning an image that is projected onto the retina.
What does the lens need to be functional?
Needs to be transparent,
Have a higher refractive index than the medium its suspended in,
Have flexible refractive surfaces with the proper curvature
What two types of epithelial cells make up the lens?
cubodial cells and elongated fiber cells
what do the epithelial cells of the lens secrete?
the lens capsule
What is the germanitive zone?
Region near the equatorial margin of the lens epithelium, where cells proliferate slowly.
True or False. Posterior Y sutures are upright.
False. posterior = inverted Y, anterior = upright Y
Where do the zonules originate?
Non-pigmented layer of the ciliary epithelium
Where do the zonules insert?
Lens capsule near the equator
How much crystallin does the lens have compared to typical cells?
3x higher
what allows for transparency of the lens?
Regular structure of lens fibers,
The absence of membrane-bound organelles,
Small/uniform extracellular space between fiber cells
True or False. Aphakia is the substitution of the natural crystalline lens with a synthetic lens.
False.
Aphakia: is the absence of the natural crystalline lens, from natural causes or removal.
Pseudophakia: is the substitution of the natural crystalline lens with a synthetic lens.
What is the role of the α-crystallin genes , αA and αB?
Prevent protein aggregation and precipitation
What percent of the lens is made of water?
65% water
What gives lens its birefringent property?
microtubules
What effect does increased cholesterol have on fibers?
Makes it more rigid.
