Structure of the Eye and Ear

iffany Goff

Margaret Jenkins

General psychology

7/11/04

Structures of the eye and ear

We use our ears for the hearing sense, and we use our eyes for vision.

Both are very important senses and would be hard to get along without.

We rely on hearing for communication, navigation, entertainment and many

other purposes

Now for our eyes we use them for vision, their like our own personal camera’s,

both have and use lens to focus on images.

The eyes respond to the visible spectrum, this spectrum is made up of

wavelengths of different sizes. The shorter waves produce a purple color, while

Longer wavelengths produce blue, yellow, green and orange, and the longest

Waves are red. Saturation, brightness, and hue all are components used in the

Visible spectrum.

More than half of the sensory receptors in the body happen to be

located in the eyes, also the cerebral cortex plays a large role in processing

Visual information.

Some accessory structures of the eye are: the eyelids, eyelashes, eyebrows,

Lacrimal apparatus, and the extrinsic eye muscles. The eyelids or (palpebrae)

Are used for shade, whether it’s for sleeping or from excessive light, or from

foreign objects that don’t belong in the eye. While the eyelids are protecting

The eye it also helps at the same time by spreading lubricates over the eyeballs.

The eyelashes help protect from foreign objects and perspiration, as well do the

Eyebrows . The Lacrimal apparatus is a group of small structures, when humans

Express emotions with tears, the Lacrimal apparatus helps to produce and then

Drain those tears away. There are six extrinsic eye muscles to help move each

Eye; the superior rectus, inferior rectus, lateral rectus, medial rectus, superior

oblique and inferior oblique. Circuits in the brain stem and cerebellum tell these

muscles what to do.

The structure of the eye begins with the fibrous tunic, vascular tunic

And the retina. These are all on the wall of the eyeball, the fibrous tunic consist of

the cornea and the sclera. The cornea is what covers the iris, and is the

outermost layer of the eye through which light passes. The sclera or the “white”

of the eye, this is what gives form to the eyeball. The vascular tunic has three

parts to it; the choroids, ciliary body, and the iris. The choroids is what provides

nutrients to the surface of the retina. The ciliary body consist of ciliary muscle

and the iris which is the colored part of the eye, it regulates the amount of light

entering the vitreous chamber, through the pupil.

The inner coat and the beginning of the visual pathway is the retina, the fovea

defines the center of the retina, and is the region of highest visual activity.