AP Bio eye structures and functions
Aqueous humor
(produced by ciliary body) Fills the anterior chamber and bathes the iris and lens; transmits light, maintains fluid pressure
Choroid
A blood vessel-rich layer of the middle eye that is darkened by the brownish pigment melanin to prevent light scattering
Ciliary muscle
A ring shaped muscle of the eye that encircles the lens and attaches to it by short fibers
Retina
Absorbs, transduces light energy
Optic nerve
Carries signals to brain
Iris
Circular muscle that adjusts the shape of the pupil to regulate how much light enters the eye
Cornea
Composed of transparent crystalline proteins
Sclera
Covers the rest of the eye's outer surface
Pupil
Entrance for light
Lens
Focuses light on the photoreceptors
Ciliary body
Holds the lens in place just behind the pupil
Conjunctiva
Protective mucous membrane that lines the inner surface of the eyelids and folds back to cover most of the eye's outer surface
Blind spot
Region of the retina through which the optic nerve exits the eye -- lacks photoreceptors so cannot respond to light
Vitreous body
Transmits light, supports lens and eyeball
