5th Class Science Human Body and their Needs Skeletal System

        Human Body

All organs work together to perform functions for the body. A group of organs doing some particular jot for the body form an organ system.

Human body has the following system performing certain function:

Respiratory system is responsible for carrying oxygen from the air to the bloodstream. Oxygen is necessary for human life.

Digestive system breaks the food we eat into smaller substances. After digestion, food can be used for producing energy.

Skeletal system gives shape to human body and helps in the movement.

Nervous system performs the functions of thinking, smelling/seeing, tasting etc.

Circulatory system helps in transportation of nutrients and other substances to various parts of the body.

Muscular system helps in movement.

         Skeletal System

It is the framework of bones which gives support to human body. Adult human skeleton has 206 bones. Different parts of the human skeleton are.

        Skull

Skull consists of 28 bones which protects the brain. All bones of skull are immovable except the lower jaw. With the help of movable lower jaw, we can talk and eat. In lower and upper jaw, we have teeth for cutting and chewing food.

          Rib Cage

Ribs make a cage of bones around the chest which is called rib cage. It protects our internal organs. Generally adults have 12 pairs of ribs. There is a long bone at the centre of the chest which holds the ribs in place which is called as sternum. Ribs are attached to the backbone. Last two ribs are not attached to the sternum and are known as floating ribs. There floating ribs are attached to the backbone.

         Backbone

It protects the spinal cord. It is made up of a series of small bones called vertebrae. Backbone is also called as vertebral column. Tigers, frogs and some other animals have backbone and are called vertebrates. Snails, earthworm and cockroaches like animals do not have a backbone and are called invertebrates.

       Limbs

All human beings have two pairs of limbs: the forelimbs (arms) and hind limbs (legs). Thigh bone or fermur is the longest bone in the body.

         Functions of the Skeletal System

The skeletal system has the following functions.

It gives shape and support to our body. Without the skeleton, our body would be floppy like a jelly. Forget about walking, we would not even be able to stand.

It protects our soft internal organs.

(i) The skull protects the brain.

(ii) The rib cage protects the heart and the lungs

(iii) The backbone protects the spinal cord.

It allows the movement of different body parts.

Bones contain marrow, where our blood cells are made.