The Skeletal System

This lesson covers: 

  1. What the skeletal system is
  2. The composition of bones
  3. The functions of the skeleton

What is the skeletal system?

Our skeletons are living systems that play essential roles in our body's protection, support, mobility, and health.

Diagram of the human skeleton showing the skull, ribcage, and spine.

The skeletal system consists of all the bones in the body.

The human adult skeleton is comprised of 206 bones.

What are bones made of?

The composition of bones allows them to be both strong and not overly heavy.

Diagram showing the outer layer and inner layer of a bone.

Bones are composed of:

  • Dense outer layer - This hard, compact area gives bones their strength.
  • Spongy inner layer - This part is light but still offers substantial support and houses the bone marrow.
  • Bone marrow - Found in the central cavities, it is crucial for producing blood cells.

The skeleton's key roles

The human skeleton has four main functions:

1. Protection - Bones like the skull and ribcage protect our organs, such as the brain and heart.

2. Support - The skeleton supports muscles and tissues, enabling us to stand upright.

3. Blood cell production - The marrow within our bones produces blood cells.

4. Movement - Muscles attached to bones, and joints help us to move.