Watch the 2 videos below to learn more about our body systems.

Respiratory & Circulatory Systems:


digestive System:


Key concepts of our Body systems:

Respiratory system

  • Our respiratory system enables us to breathe and exchange gases with the surrounding air.

  • It consists of the nose, windpipe and lungs.

  • We take in oxygen and give out carbon dioxide.

  • When we inhale (breathe in), our rib cage moves out and up. Our diaphragm moves down. As a result, our lungs expand.

  • When we exhale (breathe out), our rib cage moves in and down. Our diaphragm moves up. As a result, our lungs contract.

  • When we breathe in, air travels from the nose, down the windpipe and into the lungs. The air reaches the air sacs in the lungs. The air sacs are surrounded with many blood vessels called capillaries. Oxygen moves through the walls of the air sacs and the capillaries into the bloodstream of the circulatory system.

  • When we breathe out, carbon dioxide moves from the blood into the air sacs of the lungs where it is exhaled out of the body.


Circulatory system

  • Our circulatory system transports oxygen, digested food and water to the cells in the body. It carries carbon dioxide and other waste materials away from them.

  • It consists of the heart, blood and blood vessels.

  • The cells in the body requires oxygen and digested food to carry out respiration so as to release energy required for life processes. Note that "respiration" is not breathing.


Digestive system

  • Our digestive system breaks down food into simpler substances.

  • Digested food and water is absorbed into the circulatory system (blood stream) so that they can be used by the body.


  • Teeth chew and break up food into smaller pieces.

  • Digestive juices in the saliva break down food into simpler substances.


  • It is a muscular tube that pushes food from the mouth to the stomach.


  • It is a muscular organ that mixes the food up with the digestive juices.
  • Digestive juices break down food into simpler substances.

Small intestine

  • Digestive juices break down food into simpler substances.

  • Most digestion occurs in the small intestine. Digestion is completed in this organ.

  • Digested food is absorbed into the bloodstream of the circulatory system.

Large intestine

  • No food is digested after it enters the large intestine.

  • Water (and mineral salts) is absorbed from the undigested food into the bloodstream of the circulatory system.

Rectum and Anus

  • The undigested food is stored in the rectum before it is passed out as faeces through the anus.


Skeletal and Muscular system

  • Our skeletal system is made up of bones such as the skull, rib cage and backbone.

  • It supports the body and gives the body shape.

  • It protects organs like the brain, lungs and heart.

  • The skeletal system works together with the muscular system to help us move.



Take this quiz to recap what you have learnt. Aim to reach the moon!