Lesson overview

In this lesson students will get a first-person view of bronchial anatomy, travelling through the human body. They will then label a diagram demonstrating their understanding of the respiratory system.

Learning outcomes

• To know why lungs are necessary
• To be able to describe how the respiratory system is adapted to its function
• To be able to label a diagram of the respiratory system

Lesson steps

1. Introduction (10 mins)
   Lead a discussion around these questions: Why do we have lungs? Which gases are exchanged in the lungs? What is the larynx (voice box)? What are the adaptations of the trachea?
   Remind students that small organisms can exchange gases directly through their skin / cell membrane, but larger ones need specialised exchange surfaces in order to exchange enough gases to meet their metabolic needs (surface area to volume ratio).
   
   Challenge the misconception that we ONLY breathe out carbon dioxide. Remind students that we breathe out more carbon dioxide and less oxygen but there is not a complete exchange as they may think.
   
   Students hum / sing to feel the vibrations in their larynx. Students gently feel their trachea in their necks and notice the cartilage rings.
   
2. Expedition (20 mins)
   Lead expedition, focusing on nasal cavity, larynx and lungs. Students complete diagram on Student Sheet. During expedition ask students:
   Nasal Cavity
   
   • What is the purpose of the nasal cavity?
   • State and explain three adaptations of the nasal cavity.
   • Challenge: Some people are born with a cleft palate. This is where there is a hole in the roof of their mouth that links together the mouth and nasal cavity. What problems do you think this would cause?
     
   Larynx
   
   • What are the functions of the larynx?
   • Why do we have an epiglottis?
     
   Lungs
   
   • What is the function of the rib cage?
   • What is the function of the diaphragm?
   • Challenge: Why do the left and right lungs have different numbers of lobes? Which lung is bigger?
3. Activity (30 mins)
   After the expedition ask: Can you name the parts of the respiratory system? How is the respiratory system adapted to its function of gas exchange?
   Students watch this video of Segmental anatomy (not for squeamish viewers). Teacher checks that pupils’ diagrams are labelled correctly. Students make a flow chart to show the order in which air passes to the lungs e.g. nose / mouth.
4. Extension
   Students dissect a lung (in accordance with health and safety guidelines in your country). Students test exhaled air by blowing through lime water to prove that gas exchange has taken place (Hazard / Risk assessment should be completed).

England

Key Stage 3/4 Science

• The structure and functions of the gas exchange system in humans, including adaptations to function
• The mechanism of breathing to move air in and out of the lungs, using a pressure model to explain the movement of gases, including simple measurements of lung volume
• The impact of exercise, asthma and smoking on the human gas exchange system