Bronchi

• The bronchi are tubes that connect the trachea to the rest of the lungs. There are two bronchi and each subdivides further into a primary, secondary and tertiary part. The bronchi are made up of cartilage.
  
  

Bronchioles

• A further subdivision of the bronchi are the bronchioles, which is the first subdivision of the lung that does not contain cartilage. Bronchioles are significant because they house the alveoli.
  
  

Alveoli

• Alveoli are small small, folded sacs filled with blood vessels and they are the smallest component of the lungs. They are essential because they are where the exchanges of gases occurs in the body.