Download - 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