Organizing the body
The digestive system.^105
Breathing system: the
main organs are your
lungs, which take in air.Hormone system: this
uses powerful chemicals to
control your body and mood.Skin, hair, and nails:
these form your body’s
protective covering.Immune system: this
seeks and destroys germs
that get into your body.Urinary system: this
cleans blood and gets
rid of waste chemicals.Reproductive system:
these are the organs that
make babies.Other systems
Some of your other
important systems
are shown in this list.
Muscles
Your muscle system is made
of tissues that move parts
of your body by pulling
on them or squeezing
them. Your biggest
muscles all pull
on bones.
Your fingers
are moved by
muscles in
your arm.A long, twisting tube
makes up your
intestines, where
digested food is
absorbed.Your brain is the
nervous system’s
control centre.Your mouth is the first
part of the digestive
system.Nerves
Your nervous system carries
electrical signals around
your body. You need
this system to see,
hear, think,
and react.Senses, such as
touch, rely on
nerve cells that
send signals to
your brain.
Muscles change
the position of your
skeleton by pulling
different bones.Signals shoot
along nerves to
muscles,
telling them
when to pull.Digestive system
Your digestive
organs break
down food to
provide your
body with energy
and raw materials.Skeleton
Bones and
joints make
up the skeletal
system, an
inner frame
that supports
the body.The most powerful
muscles are
in your legs.A quarter of
your bones are
in your feet.Your mouth is the first
part of the digestive
system.