what are the lungs made of? – Secondary 11

Question: what are the lungs made of?
- Keywords:
  lungs,
  organ
Asked by jhorsnall to Jemma, John, Katie, Lisa on 28 Jun 2012.
- Jemma Ransom answered on 28 Jun 2012:
  
  Hi @jhorsnall,
  
  the lungs are made of billions of cells that form sac-like structures called alveoli. These fill with air when you breathe in and create a huge surface area for oxygen to diffuse across into the blood stream.
  
  Jemma

Question: what are the lungs made of?