4. The digestive system is one of the body’s major organ systems. When
you are eating something, your digestive system goes to work. Its job is
to break down food into nutrients that the body cells can use. The
process of breaking down food is called digestion.
5. You could not live for very long without breathing in and breathing
out. Organs that work together to take air into the body and push it
back out make up the respiratory system.
6. Blood not only brings oxygen to the cells and takes away carbon dioxide.
It also transports nutrients and water to the cells. The job of the
circulatory system is to transport oxygen, nutrients, water, and wastes.
7. The skeletal system is the system that gives the body shape and support,
protects the organs inside the body, and works with the muscles to move the
body.