Page 27 - Viva ICSE Science 5 : E-book

• Support: Bones provide attachment points for muscles and other tissues. Bones
of legs and vertebral column hold up the body. Nearly all organs are supported by
bones in one or the other way.

• Movement: Diff erent voluntary movements (bodily movements that are under the
control of our will) are performed due to the combined action of skeletal muscles,
bones and joints.

• Production of blood cells: Red blood cells and white blood cells are produced by a

jelly-like substance called bone marrow present inside the bones.

• Mineral storage: Bones store minerals like calcium and phosphorus, and helps in
maintaining the levels of these minerals inside the body.

TIME TO REVISE

Fill in the blanks.
1. There are _____________ bones in an adult human body.
2. The skull consists of a total of _____________ bones.

3. A protective cage around the heart and the lungs is called the _____________.
4. A jelly-like substance called _____________ is present inside the bones.

Joints

The places where two or more bones meet or join together are called joints. The bones
are held together at the joints by strong tissues called ligaments. It is due to the presence
of the joints that we can bend and move diff erent parts of our body.

Types of joints

Joints are of two types—movable and immovable. Most of the joints are movable except
the joints in the tooth socket and in the skull. There are four types of movable joints—

the hinge joint, the ball and socket joint, the pivot joint and the gliding joint.

Hinge joint

Hinge joint allows back and forth movement
in one direction only, similar to the hinges of a

door. Bones in the elbow, knee, toes and fi ngers
have hinge joints.

Hinge joint

13