2.2 Skeleton

Summary: Most parts of your body have hard structures inside them. These are your bones. They help form your shape, allow you to move, and have other important roles. Tags: science oxford-science student-book-7 biology Created: 2026-05-19 Last Updated: 2026-05-19

After this topic, you will be able to:

• label the main bones in the human skeleton
• describe the structure of a bone
• describe the functions of the skeletal system.

Think back

1. Which structure protects the lungs?
2. What do muscles do?
3. What do red blood Cells do?

Key idea As well as allowing us to move, the skeleton supports and protects us. It also makes blood cells.

Key words bone, skeleton, muscular skeletal system, bone marrow

Most parts of your body have hard structures inside them. These are your bones. They help form your shape, allow you to move, and have other important roles.

What are bones?

Although bones in a museum are old and dry, the bones in your body are different. Bone is a living tissue with a blood supply. It is growing and changing all the time. Just like other parts of your body, it can repair itself when damaged, like the broken bone in Figure 1. Calcium and other minerals make the bone strong. Exercise and a balanced diet are important to keep your bones healthy.

Figure 1Doctors use X-rays to check if a bone is broken.

What is a skeleton?

Together, all the bones in your body make up your skeleton. They join together to form a frame. The average adult human skeleton consists of 206 bones, some of which are labelled in Figure 2. Your skeleton is part of your muscular skeletal system.

Figure 2The main bones of the human body. Full text alternative to the content

A Identify the two bones in the lower leg.

Why do we have a skeleton?

The skeleton has four main functions:

• to support the body
• to protect important organs
• to help the body move
• to make blood cells.

Support

The skeleton provides support for your body and holds your organs in place inside your body. Without bones, the body would fall down. The bones create a frame for your muscles and organs to connect to. Your vertebral column (backbone) holds the body up and straight.

Protect

Bones are hard and strong so they can protect important organs from damage. For example:

• Your skull protects your brain.
• Your ribcage protects your heart and lungs.
• Your backbone protects your spinal cord.

Move

Muscles are attached to bones. If a muscle pulls on a bone, the bone will move. The skeleton moves at joints, such as your knee. The movement of bones at joints allows the body to move.

B Name the tissue that causes your skeleton to move.

Making blood cells

Some bones inside your body are not solid. For example, the long bones in your arms and legs. In the middle of these bones is a soft tissue called bone marrow. You can see this in Figure 3. The bone marrow produces red and white blood cells. Red blood cells carry oxygen around the body. White blood cells protect against infection.

Figure 3Structure of a bone.

C Identify the outer layer of bone which makes bones strong.

Stretch zone

1. Copy and complete the sentences. Your skeleton is made up of bones/cellulose. The skeleton has four important functions – to stretch/support the body, to protect/support organs, to help the body move, and to make blood/oxygen. Red and white blood cells are produced in bone marrow/minerals which is found in the centre of some bones.
2. State two features of the structure of a bone.

Stretch zone

1. Answer the questions. Describe the function of the skull.One function of the radius is to produce blood cells. Explain one other function of the radius.