When we think about what a bone is
made of, we usually imagine it to be a dry and hard
substance that doesnt appear to be living
in any way.
In fact, the bones in our bodies are
filled with living material: there are blood
vessels which run near the surface of the bone,
and two layers of bone types, compact
bone and spongy bone.
Often there is a jelly-like area in the centre of the
bone, which is called the bone
marrow. Bone marrow produces the body's blood
cells. Red blood cells carry oxygen around the body
and white blood cells fight infection within the body.
||If you looked at
a cross section of your arm, you would be able to
see that the bone is actually a hollow structure;
in the middle is a cylinder.
||So, bones are actually
hollow tubes, a bit like bamboo which is a type
of plant. A hollow structure means that the weight
of the bone is a lot less than it would be if it
But try applying force on the top
and then the sides of a drink can. What happens? What
price do we pay for having light bones?
| Launch it ...
Have a look at the Extreme
Limits and see what happens when different forces
are applied to bones. What do these clips have in
common (apart from being gory!)?
(WARNING: EXTREMELY GORY)
| Did You Know ...
If you have already seen Casing
the Joint youll already know the answer to
Different types of animals have different
skeletons, depending upon what they need them to do.
||Bones in the human
body are not only concerned with forming a strong
structure which holds our bodies up and helps us
move; they are also there to protect our internal
organs. For example, if you didnt have a ribcage,
your heart would be very vulnerable. Bones also
store essential body minerals, and bone marrow produces
new cells for our bloodstream.
Our bodies are constantly replacing
bone tissue and our ability to do this is dependent
upon the minerals we have in our blood.
| Discuss it ...
What do you think would happen to your
bones if you didnt have the right kind of
minerals in your blood?
| Did You Know ...
is a condition that can occur if the body cannot make
enough new bone building material. This is because the
person does not have the right mineral levels in their
bloodstream. The result is that bones become larger
and more fragile.
It is unusual for young people to
suffer from osteoporosis, but your diet and lifestyle
will affect your health in later life so you need to
ensure that your diet is rich in calcium.
For more information, visit the National
In a transplant, a patients damaged bone marrow
is destroyed and healthy marrow is introduced into the
blood stream. The new tissue migrates to the cavities
within large bones and begins to produce healthy blood
cells once more.
is a condition that makes the joints swell. This swelling
is the result of bones rubbing against each other without
the protection of cartilage.
If you suffered from arthritis of the knee, you would
be unable to straighten or bend your knee fully and
moving it would be very painful.
Sadly there is no cure for this condition,
but joints may be replaced with steel or plastic to
make artificial bone and cartilage.
For more information about arthritis,