Reading Comprehension/human Body printable pdf download

Reading Comprehension/Human Body

Name ____________________________________________ Date _______________

The Human Eye

You use your five senses to understand the world around you and to figure out what’s

going on. One of your five senses is sight, and it is with your eyes that you see the

world. Eyes are constantly working, from the time you wake up in the morning to the

time you go to sleep. Let’s take a closer look at the human eye!

The eye is about 2.5 cm in length, weighs about seven grams and is shaped roughly

like a ball. It sits in a special place in your skull called the eye socket. When you look in

the mirror you can see several parts of your eye. The white part is called the sclera. The

sclera is very tough and covers most of your eye. If you look very carefully you can see

little red threads, which are tiny blood vessels bringing oxygen to the sclera. If you rub

your eyes a lot, some of the tiny vessels break, and that is why your eye sometimes

looks a little pink. The sclera covers the colored part of your eye as well, but here it is

clear, and has a different name: the cornea. The cornea is very important because it lets

light come into your eye. It also helps the eye to focus as light passes through. The

colored part of your eye is called the iris. In the middle of your iris is the black pupil.

Light first travels through the cornea, and then into the pupil. There are tiny muscles

attached to the iris that help control the amount of light that can get through. In very

bright light, the pupil will get smaller, and when it is darker, the pupil will get bigger, just

like a camera lens. Between the iris and the cornea is the anterior chamber. Anterior

means “front”. The anterior chamber is filled with a clear liquid called the aqueous

humor. The aqueous humor provides oxygen, proteins and glucose (sugar) to the eye.

IRIS

SCLERA

AQEOUS HUMOR

RETINA

CORNEA

LENS

OPTIC NERVE

VITREOUS HUMOR

After light passes through the pupil, it passes through the lens. The lens is roughly the

shape of a squished ball, and it is completely clear. The lens’s job is to focus the stream

of light coming through the pupil onto the back of your eye, which is called the retina.

The lens is attached to a muscle called the ciliary muscle. This muscle causes the lens

to actually change shape as you focus on things! When you look at something very

close to you, the lens gets thicker, and when you look at something far away, the lens

gets thinner!

Between the lens and the retina is a gel-like clear material called the vitreous humor.

The vitreous humor is important because it gives the eye its shape.

Reading Comprehension/human Body