The human eye

The Human Eye

Prepared by:Lorlie A. AbieraMaster Teacher IAntique Vocational SchoolBugasong, Antique

How do we see things?

Light makes us see……

The Sun…… gives us light

The Eye – organ for seeing Human eye – one of

the most complicated optical system

-almost spherical in shape, about 2.5 cm in diameter

-the front part is covered by the cornea, the back part is covered by the retina

Parts of the Human Eye

Cornea – the transparent outer membrane which forms the eyeball’s outer coating.

- it serves as the window of the eye

Lens – is a jelly-like assembly of tiny transparent fibers Its main function

is to bend light rays that enter the eye

Iris – the colored part of the eye in front of the lens Made up of two

different muscle fibers which controls the size of the pupil

Iridologists believe the coloration and patterns of the iris of the eye reveal information about the health and well-being of the individual.

Pupil – allows light to pass into the eyes from the aqueous humour to the lens It opens and

closes to control light entering so as not to damage the retina

In dim light the iris contracts and the pupil gets bigger. This decreases the amount of light that enters the eye.

In very bright light, the pupil becomes smaller and the amount of light that enters the eye decreases.

Ciliary muscle – contracts and expands to control the curvature of the lens

Vitreous humour – a cavity filled with liquid in front of the retina

Retina - a light-sensitive membrane in the back of the eye containing rods and cones that receive an image from the lens and send it to the brain through the optic nerve It serves as a screen

where the image is formed

cones – responsible for vision in bright conditions

rods – for dim conditions

Fovea centralis – the center of the eye sharpest vision and the location of most color perception

Optic nerve – the pathway that the light rays take from the retina to the processing center of the brain

Eye Fun Facts• Most people blink every 2-10 seconds.Each time

you blink, you shut your eyes for 0.3 seconds, which means your eyes are closed at least 30 minutes a day just from blinking.

• If you only had one eye, everything would appear two-dimensional. (This does not work just by closing one eye.)

• Owls can see a mouse moving over 150 feet away with light no brighter than a candle.

• The reason cat's and dog's eyes glow at night is because of silver mirrors in the back of their eyes called the tapetum. This makes it easier for them to see at night.

• An ostrich has eyes that are two inches across. Each eye weighs more than their brain.

• A chameleon's eyes can look in opposite directions at the same time.

• A newborn baby sees the world upside down because it takes some time for the baby's brain to learn to turn the picture right-side up.

• One in every twelve males is color blind

Which part of the human eye serves as a screen where the image is formed?

Which part of the eye bends the light rays that enter it?

It is the window of our eyes…

It is the part of the eye where the light rays enter….

It controls the opening of the pupil….

What is the position of the image in the retina?

What is the shape of the lens when you looked at far objects?

It is the passageway of the message from the eyes to the brain…..

Complete the statement below.. My eyes are important because……

Proper Care of my Eyes Have enough sleep Eat nutritious foods Practice proper ways in reading or in

studying Don’t wash your eyes when it is tired Don’t rub your eyes with your dirty

hands Don’t watch TV at very near distance