Inside Your Body

Inside Your Body

Introduction The human body is an amazing machine. It has many parts that form systems. The systems work together to keep you alive and healthy. Let's look at some of your body's systems.

Skeletal System There are 206 bones in your body that make up your skeleton. Your bones give your body shape and strength. They also protect your inner organs. Most of the bones in your body are linked together at joints. There are different kinds of joints. Different joints let body parts move in different ways.

The joint that joins your arm and shoulder lets your arm rotate. The joints at your elbows and knees let your lower arms and legs move up and down. If it were not for moving joints, you could not walk, run, and swim.

Muscular System Muscles control the movement of your body. There are three kinds of muscles. Skeletal muscle is the muscle that is attached to bones. It makes your arms, legs, fingers, eyes, and other body parts move. Cardiac muscle is the strong heart muscle. It works around the clock. Smooth muscle is found in your skin, stomach, and other organs.

Nervous System Your brain and thousands of miles of nerve fibers form your body's communication system. The brain is the control center. It receives information from your sense organs--eyes, nose, ears, tongue, and kin. The brain tells muscles what to do. If your fingers go near something hot, a signal goes to the brain. It then sends a signal to tell your hand to move away.