the Support Systems by natasha

The skeletal system and muscular system

The skeletal system and muscular system.

The muscular system. The bones of the the body have no way of moving themselves. The muscles of the body must move the bones. In fact, half of your body is muscle! Muscles work in two different ways. They get longer and shorter. When the muscles relax and get longer, they move the bones. Muscle is thick in the middle and thin on the ends. The thin end of the muscle is hooked to a bone. It is hooked by a strong, tough cord called a tendon. Tendon and muscles move the bones in your foot. Tendons and muscles move all of the body. Did you know there are more than 600 muscles to move the skeletal system. The bones of the body are called the skeleton or skeletal system. There are 206 bones in the body. The bones are many shapes and sizes. Bones are hard on the outside, but are soft on the inside. The soft, inside part of the bone is called marrow. Blood vessels and nerves are also found inside the bones. The bones have important jobs. If you did not have bones, your body would not be a pile of skin, muscles, blood vessels, and other parts! Another job of the bones is to keep parts of the body from getting hurt. The ribs protect the lungs and heart. The backbone protect the nerves inside it. Can you guess what the skull protects? All of the skeleton is not made of bones. Some of it is made out of cartilage. Cartilage is a tough, stretchy tissue. It is hard, but not as hard as a bone. It helps give your body shape. A broken bone will grow back together. But the broken parts must be kept from moving. Food helps to mend the bone. One of the most important parts of the skeleton is the backbone. It is sometimes called the spine.