with the rest of the
body, flexible as
there are lots of
joints, organs are
framework for the
body, flexible due to
takes a long time to
a material called
Advantages: Can be
need to shed their
Internal skeletonshave many
advanatges over external skeletons: It
provides an internal framework for the
body, grows with the rest of the body, is
flexible due to the many joints and it
allows easy attachment of muscles
Endo over Exo
Bones and cartilage
Cartilage and bone are living tissues
containing living cells, this means
they can be infected by bacteria and
viruses. However they are able to
grow and repair themselves.
A long bone contains of a long shaft
containing bone marrow with blood
vessels. At each end there is a head
covered with cartilage. Long bones are
hollow, so they are stronger and lighter
than solid bones.
At birth the human skeleton is
made of cartilage. Ossification is
the proccess of slowly replacing
the cartilage by bone. If some
cartilage remains between the
head and shaft - the bone is still
In an accident it can be
dangerous to move a person
with a suspected bone fracture.
Broken vertebrae in the
backbone can damage the
spinal cord, resulting in
paralysis or death.
Even though bones are very strong they
can easily be broken by a sharp knock.
The bones of elderly people can lack
calcium and phosphorus which often
results in osteoporosis making them
prone to fracture.
There are threee types of
fracture: simple (straight break),
compound (comes out of skin)
and greenstick (bone not
Joints and Joint Replacement
A joint is where two or more bones
meet and muscles act together to
Antagonistic pairs - muscles
working together, as one
contracts another relaxes.
The forearm is raised and lowered
by antagonistic muscles - the
biceps and triceps. To raise the
biceps contract&triceps relax and
This is an example of a
lever, with the elbow
acting as a pivot.
Coral and liquid bones can be
used as joint replacements
however artifical substances are
at risk of not being accpeted by
the immune system.
Advantages - it allows patients to live more independantly,
improves their quality of life, accidental injuries and
amputations can be avoided and there is no worry about
Synovial joints, such as ball
and socket joints and hinge
joints, contain synovial fluid,
a synovial membrane,
ligaments and cartilage.
Each part of the synovial joint has a special
function: the synovial fluis acts as a cushion against
shock and a lubricant for easy movement. A
synovial membrane holds in the fluid. The cartilage
protects protexts the bone head. The ligaments
hold the bones in place.
A ball and socket joint has
a wider range of movement
than a hinge joint ( these
can only go up-and-down)