After Quiz 6 Flashcards
Cornea
Transparent & circular front part of the eye that covers the: iris, pupil, & anterior chamber
Provides most of eye’s optical power
Light hits the cornea, bends (refracts) incoming light onto the lens
Sclera
Opaque, fibrous, & collagenous protective layer of the eye
Helps maintain rigidity
Limbus
Corneoscleral junction
Where cornea meets sclera
Uvea
Deep to sclera
Consists of choroid, ciliary body, & iris (contains the pupil)
Choroid
Vascular layer of the eye, located between the retina & the sclera
Ciliary body
Located between iris & choroids
Contains many muscle bundles that regulate the shape of the lens
Iris
Overlays the lens
Controls the amount of light that enters the eye (along with the pupil
Made of thin, elastic tissue with an opening (pupil) in the center; surrounded by a circular muscle (the sphincter)
It contains pigmented epithelium
Pupil
Controls the amount of light that enters the eye (along with the iris)
During low light = expands
During high light = contracts
Retina
Thin layer of neural cells along the back of the eyeball
Where light is converted into electrical impulses & sent along the optic nerve to the brain
Made of rods (dim light vision), cones (color vision), & photoreceptor cells
Zonule
Suspensory ligaments of the lens
Composed of zonular fibers
- Change tension via contraction & relaxation of the ciliary muscle to change the focusing power of the eye (contradictory)
Lens
Biconvex, transparent, & elastic structure that focuses the light coming in through the cornea & pupil
Loses its accommodation ability as the individual ages (called presbyopia)
Three parts:
- Lens capsule
- Lens epithelium
- Lens fibers
Lens capsule
Elastic & composed of collagen
Lens epithelium
Regulate most of the homeostatic functions of the lens
Lens fibers
Form the bulk of the lens
Vitreous humor
Clear, jelly-like aqueous solution that fills the space between the lens & retina
maintains the shape of the eyeball & provides clear path for light to travel to the retina
Aqueous humor
Fills the space between the cornea & the lens
Provides nutrients to the lens & corneal endothelium
Its pressure maintains the convex shape of the cornea
Anterior chamber
Fluid filled space between the cornea & iris
Posterior chamber
Narrow cavity between the iris & lens
Scleral sinus
Critical area for drainage of aqueous humor from the eyeball
*failure to drain = inc. intraocular pressure (glaucoma)
Tapetum lucidum
Light-colored, reflective area of choroid
Reflects light rays (improves vision in low-light conditions)
Found mostly in nocturnal animals
Nontapetal nigrum
Brown-black portion of interior of the eyeball
Optic disk
Entrance of optic nerve into posterior aspect of the eyeball
Contains no rods or cones (called the blind spot)
External jugular vein
Formed by meeting of linguofacial & maxillary veins