Lungs

• The trachea is the tube that carries air from the mouth to the lungs
• The two bronchi are the tubes that carry air from the trachea to the each lung
• The alveoli are where gas exchange take place
• The lungs contain air sacs called alveoli which are surrounded by a network of blood capillaries
• Oxygen diffuses out of the alveolus and into the blood stream
• Carbon doixide diffuses out of the blood and into the alveolus to be breathed out