The document discusses breathing and the respiratory system. It aims to help students understand the role of the respiratory system in humans, how breathing links to cellular respiration, and visualize how the lungs work using a model. Key parts of the respiratory system that are mentioned include the ribs, bronchioles, bronchi, trachea, rib muscles, lungs, and diaphragm. The alveoli in the lungs are where gas exchange takes place.

3. The Respiratory System Ribs – to protect the chest Bronchioles Bronchi Trachea – has stiff rings of cartilage to prevent it collapsing Rib muscles – to raise and lower the ribs Lung Diaphragm – muscular sheet Alveoli (“air sacs”) – gas exchange takes place here

6. Why are these so different? Explain why we need to take in oxygen and get rid of carbon dioxide.