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Living bone (Skeleton and bones)

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					Skeleton       and   bones

Living bone
Their outer surface may be hard                                  Marrow can be found
                                                                 in the spine, skull,
and dry but that doesn’t mean                                    and the main leg and
                                                                 arm bones.
your bones aren’t alive. Bones
are always growing and
repairing themselves.
What’s inside our bones?
Bone accounts for one
sixth of your body’s
weight. Its clever
structure means
it’s often
lighter than
it looks.


Spongy bone
Parts of some bones have a
honeycomb structure with lots of                                          Bone marrow
spaces. This makes them weigh less                                        A jellyish substance
than if they were solid right through.                                    called marrow fills
                                                                          the centre of many of
                                                                          your larger bones. It
                                                                          supplies your body
                                                                          with red blood cells
                                                                          at a rate of 3 million
                                                                          cells per second.


                                                 Compact bone
                                          The hardest and most
                                    dense part of the bones is
                                   the outer layer. It is made
                                      of calcium, a substance
                                  we get from our food. Teeth
                                    are made of calcium too.
18
         What are the most commonly broken bones?
                                                                            Living bone
          Broken bone                                                   Curiosity quiz
   Bones are strong and
flexible enough to cope                                                Take a look through
  with a lot of pressure,                                             the skeleton and bones
      but, as this X-ray                                               pages and see if you
 shows, they sometimes                                               can identify where these
    break. Luckily they
   can heal themselves.                                                bony bits come from.

                                 If the broken bone
                                 ends have slipped
                                 apart they must
                                 be repositioned
                                 by a doctor before
                                 healing begins.
                                                          Become
                                                        an expert...
                                                         on the skeleton,
On the mend                                                pages 12-13
New cells form at each end of
                                                        on skin and nails,
the broken bone, closing the
gap between them. It takes                                 pages 70-71
about 6 weeks for this
to happen.
                          s.




                                                 Padded clothes
                      teen




                                                 help protect
                                                 bones from
                re still




                                                 sudden impact.
          your late
           es a




                                         Looking after
                                         your bones
         on




                                         Calcium from
     b
   ur unt
       il




                                        milk and cheese
 Yo ing                                 is needed to build
                                        strong bones.
grow                               Weight-bearing exercise
                                   like walking, climbing,
                                   or skating helps to
                                   strengthen bones.



                                Fingers, wrists, and arms.                                 19

				
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posted:10/10/2012
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