Look out! (Brain and senses) by hamada1331

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									Brain   and   senses

Look out!                                                                    Wandering eyes
                                                                             Six muscles control each eye.
                                                                             You use both eyes when you
Sight is the body’s main sense and                                           look at something, so your
the main way we learn about our                                              eyes move together.
surroundings. Two-thirds of the                                                                              Sclera (or white
                                                                                                             of the eye)
information we take in comes
from our eyes.                                                                                                       Iris




                                                                                                                    Pupil



                                                                                                          The middle of the
                                                                                                          eyeball is filled
                                                                                  The muscles             with fluid.
                                                                                  surrounding your
                                                                                  eyeball make precise
                                                                                                                ue t
                                                                                  movements so you can
                                                                                  smoothly track moving       iq i n
                                                                                                                r



                                                                                                  fin un
                                                                                  objects.
                              At




                                                                                                         p
                                                                                                     ger
                                                                                            as a i s as
                                 n
                     igh




                                                                             y.




                                                                                               ri s
          t, o




                                                                            a
                                                                         aw




                                                 Pupil     Eyelid
                                                                                         An i
              ur eyes could




                                                                   mile)(1




                                                                                Hidden away
                                                                                Most of your
                                                                     km




                                                          Sclera
                                     Iris                                      eye nestles
                          et                                                  safely in its
                                                               1.6
                     d




                             ec                                             socket and is
                                  ta
                                            lighted c    an dle            protected by pads of
                                                                           fat. On the outside,
                                                                            you can see the iris,
                                                                                   pupil, and some
                                                                                       of the sclera.


38
                                What is the sleep that collects in our eyes?
                                                                                                          Look out!
  Tears are made behind                                Safekeeping                               Eye colour
  each eyelid.                                                                                   The iris is the coloured
                                                       Your eyes are fragile,                    part of the eye. All eye
                                                       squidgy balls made of                     colours are produced by
                                                       watery jelly so they need                 one substance, melanin.
                   Tears drain into tear ducts.        to be well protected.                     Lots of melanin results
                   These link to your nose,                                                      in brown eyes, less
                   which is why your nose runs                                                   means a lighter shade.
                   when you cry.                                   Bone in your skull
                                                                   surrounds your brain
Crying                                                             and the backs of the eyes.
Tear glands behind your eyes
produce drops of salty fluid.                                      Eyebrows sit above your
                                                                   eyes and prevent sweat
When you blink, your eyelids                                       dripping into them.
sweep this fluid over your eyes
to keep them clean. If something                                   Eyelids and lashes stop
gets into your eye, or you feel                                    dust entering the eyes and
                                                                   then sweep it well away.
strong emotions, the drops turn
into floods of tears.
                                                          pils chang
                                                 u   r pu           e siz        atically.
                                              Yo                         e autom




                                                                      Either it’s dark or this
                                                                            person has seen
                                                                             something they
                                                                                         like.


                                                                            Pupil size
                                                                            The pupil is the
                                                                             opening that
                                                                             controls how
                                                                             much light
                                                                            enters your
                                                                            eye. It’s smaller
                                                                           in bright light to
                                                                          protect the nerve
                                                                         cells in your eye,
                                                                       and bigger in dim
                                                                     light to let more light
                                                                   in. It also gets bigger
                                                                when you see something
                                                                or someone you like.
                            Dust and mucus washed from our eyes as we sleep.                                           39

								
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