How Internal Structures Keep Animals Alive

Animals have many parts inside their bodies that work together to keep them alive. These parts are called internal structures—body parts found inside an animal. Each internal structure has a special job, and all of them must work together for the animal to survive.

The skeleton is a framework of bones that supports the body and protects important organs. Without a skeleton, your body would be like a tent without poles—it would collapse! The heart is a muscle that pumps blood through the body, delivering oxygen and nutrients to every cell. Think of the heart as a delivery truck that never stops working.

Animals need oxygen to survive. Lungs are organs that take in oxygen from air, while gills are organs that take oxygen from water. Fish have gills because they live underwater, but humans and many other animals have lungs because they breathe air.

The stomach and intestines work together to digest food. The stomach breaks down food into smaller pieces, and the intestines absorb nutrients the body needs for energy and growth. Finally, the brain controls everything. It sends signals to all body parts, telling them what to do and when to do it.

Different animals have different versions of these structures depending on where they live and what they need. Without any one of these internal structures, an animal could not survive.

Interesting Fact: A giraffe's heart weighs about 25 pounds and must pump blood all the way up its long neck to reach its brain!