Unit 1 pt 2

Front

Iris

Back

A ring of muscle tissue that forms the colored portion of the eye around the pupil and controls the size of the pupil opening.

Front

Lens

Back

The transparent structure behind the pupil that changes shape to help focus images on the retina.

Front

Retina

Back

The light-sensitive back inner surface of the eye, containing the receptor rods and cones plus layers of neurons that begin the processing of visual information.

Front

Accommodation

Back

The process by which the eye’s lens changes shape to focus images of near or far objects on the retina.

Front

Rods

Back

Retinal receptors that detect black, white, and gray, and are sensitive to movement. Necessary for peripheral and twilight vision, when cones don’t respond.

Front

Cones

Back

Retinal receptors concentrated near the center of the retina that function in daylight or well-lit conditions. Detect fine detail and give rise to color sensations.

Front

Optic Nerve

Back

The nerve that carries neural impulses from the eye to the brain.

Front

Blind Spot

Back

The point at which the optic nerve leaves the eye, creating a “blind” spot because no receptor cells are located there.

Front

Fovea

Back

The central focal point in the retina, around which the eye’s cones cluster.

Front

Young–Helmholtz Trichromatic (Three-Color) Theory

Back

The theory that the retina contains three different types of color receptors — one most sensitive to red, one to green, one to blue — which, when stimulated in combination, can produce the perception of any color.