Page 26 - (DK) How to be a GENIUS?

Eye muscle One of six
muscles that rotate the
eye in its socket

Choroid A network of
blood vessels spreads
through this middle
layer of the eye.

Retina The inner
lining is a sheet of
light-sensitive cells.

W e ar e visual cr eatur es. W e identify mos t things by sight
We are visual creatures. We identify most things by sight
and we think mainly in visual terms. So for most of us,
sight is our dominant sense. This means that a lot of
the information we commit to memory is in the form
of visual images. But how do the brain and eyes
work together to create these images?
wo

Pupil The o
P pening
i n the iris al llows
l
Image convertor light into th e eye.
Your eye is a ball of transparent jelly lined with light-sensitive
cells. Light rays enter your eye through lenses that focus an L Lens The el lastic lens
c
changes sha ape to
upside-down image on the cells. These cells respond by fine-focus t he image.
fi
generating tiny electrical signals that pass down a bundle
of nerve fibers to your brain. The cells exposed to parts of
the image that are light generate bigger signals than cells
raa
exposed to dark parts, just like the pixels in a digital camerra
sensor. The cells turn the image into an electronic code
that your brain can process.
Clear view
Light reflected from

Reflected light anything you see is focused
Visible objects by the cornea and lens to
ect

light
reflect light into b form a clear optical image.
r
efle
to
o

in
This is projected upside
your eyes. .
down on the back of the eye.
f
T
d
e
Iris Muscles in n the
c
ze
he
iris change the si size
of the centralal pupil.
tr
upil
“
Cornea The ““wind dow” at
the front of the e e eye e partly
the
focuses t th image.
Automatic control
Each eye has two lenses. The cornea at the
front forms one lens. Behind this is another
lens made of transparent jelly, suspended
by muscles that automatically change its Sclera The white
shape to focus on close or distant objects.
The colored iris controls the light entering of the eye forms a
tough outer layer.
the eye by automatically dilating (widening)
or contracting the pupil at the centre.
Dilated Contracted
pupil pupil
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