The respiratory system is made up of many parts. The diagram shows the respiratory system in humans:
The nose (and nasal cavity) form the first port of entrance of air into our body. The mouth can be used as a secondary entrance when needed.
The nose and mouth are connected to the trachea (windpipe). The trachea allows air to pass through to the lungs.
Towards its end, the trachea splits into two branches, the left and the right bronchus (plural: bronchi). Each bronchus leads to a lung. The bronchi keep separating into branches, which in turn separate into smaller branches: these are the bronchioles that spread throughout the lungs. Each bronchiole ends in a tiny air sac called an alveolus (plural: alveoli).
All of these structures and organs enable us to use oxygen from the air we breathe in and remove carbon dioxide, which is poisonous to us. The oxygen is used in a chemical reaction that takes place in all cells called aerobic respiration. We need respiration to give us energy for all sorts of processes, like movement and growth.
The respiratory system and the digestive system work together as the oxygen (from the lungs) reacts with the glucose provided by the food we eat. Energy is released when this happens and water and carbon dioxide are produced. The carbon dioxide is removed from our body when we exhale. Water is released in our sweat, urine and also as droplets in our breath when we talk and breathe.
Respiration doesn't just happen in humans - it occurs in all living organisms and happens in both plant and animal cells.
We can summarise aerobic respiration using a word equation:
Glucose + Oxygen → Carbon Dioxide + Water
The glucose and oxygen are the reactants in this reaction. They react with one another.
The carbon dioxide and water are the products in this reaction. They have been produced, or made in this reaction.
Take care not to confuse breathing in and out with respiration: breathing provides the oxygen needed for respiration and removes the carbon dioxide.
In this activity, we are going to recall what happens in aerobic respiration.