The Skeleton

What are the functions of the skeletal system?

To retain their shapes, all organisms need some type of structural support. Unicellular organisms have a cytoskeleton that provides structural support. Multicellular animals have cytoskeletons within their individual cells, but a skeleton is needed to provide support for the whole body. These skeletons include the external exoskeletons of arthropods and the internal endoskeletons of vertebrates.

Structure of the Skeleton There are 206 bones in the adult human skeleton. As you can see in Figure 32–1, some of these bones are in the axial skeleton and others are in the appendicular skeleton.

The axial skeleton supports the central axis of the body. It consists of the skull, the vertebral column, and the rib cage. The bones of the arms and legs, along with the bones of the pelvis and shoulder area, form the appendicular skeleton.

Functions of the Skeletal System The skeletal system has many important functions. The skeleton supports the body, protects internal organs, assists movement, stores minerals, and is a site of blood cell formation. The skeletal system supports and shapes the body much like an internal wooden frame supports a house. Bones also protect the delicate internal organs of the body. For example, the skull forms a protective shell around the brain.

Bones provide a system of levers on which muscles act to produce movement. Levers are rigid rods that can be moved about a fixed point. In addition, bones contain reserves of minerals, mainly calcium salts that are important to body processes. Finally, new blood cells are produced in the soft marrow tissue that fills cavities in some bones.

In Your Notebook Use a two-column table to list the roles of the skeletal system and an example of each role.