Eyes Flashcards
What does contraction of the ciliary muscle do?
Contraction of the ciliary muscle changes the shape of the lens, which enables it to bring light rays from different distance to focus on the retina.
What part of the eye contains light sensitive receptors and complex neuronal networks?
The neural retina
What part of the eye contents simple cuboidal melanin-containing cells?
The retinal pigment epithelium (RPE).
what protects the DNA in corneal epithelium from UV light damage.
Ferritin protects the DNA in the corneal epithelial cells form free radical damage caused by UV light exposure.
What acts as a barrier for spread of infection in the eye?
Bowman’s membrane imparts some strength to the cornea, bur more significantly , it acts as a barrier to the spread of infections. It does not regenerate. Therefore, if damaged, an opaque scar forms that may impair vision.
Which layer of the cornea is PAS-positive and can regenerate?
The descemet’s membrane. It readily regenerates after injury, it is produced continously but slowly thickens with age.
Changes in what structure of the sclera can cause glaucoma?
Changes in the iridocorneal angle (the limbus region) may lead to blockage in the drainage of aqueous humor causing glaucoma.
What is the innervation of the sphincter pupillae and dilator pupillae?
What are their respective cranial nerves?
Sphincter pupillae - PNS (CN III-oculomotor)
-Responsible for reducing pupillary size in response to bright light.
Dilator pupillae- SNS (Superior cervical ganglions).
-This muscle is responsible of increasing pupillary size in response to dim light.
What part of the ciliary muscle helps with the iridocorneal angle and facilitates drainage of the aqueous humor?
• The meridional (or longitudinal) portion: consist of the outer muscle fibers that pass posteriorly into the stroma of the choroid. These fibers function chiefly in stretching the choroid. It may help open the iridocorneal angle and facilitate drainage of the aqueous humor.
What part of the ciliary muscle helps with flattening the lens and thus focusing on distant vision?
• The radial (or oblique) portion: consist of deeper muscle fiber bundles that radiate in a fanlike fashion to insert in the ciliary body. Its contraction causes the lens to flatten and thus focus for distant vision.
What part of the ciliary muscle helps with reducing the tension of the lens, causing the lens to adjust to near vision?
• The circular (or sphincteric) portion: consist of inner muscle fiber bundles oriente in the circular pattern that forms a sphincter. It reduces the tension on the lens, causing the lens to accommodate for near vision.
