The lungs are a very important organ.

• The lungs take in fresh air containing plenty of oxygen.
• Inside the lungs, this oxygen moves into the blood.
  • Blood inside the lungs is carried in tiny capillaries^* on the lining of the lungs.
  • The lining is arranged in small pockets to give it a large surface area.
  • All along this lining, air comes in contact with blood.
  • Oxygen in the air can move into the blood to be taken to all parts of the body.
• At the same time carbon dioxide moves from the blood into the lungs.
• When carbon dioxide builds up in the lungs, we exhale^* it out of the lungs.
• Then we inhale^* fresh air which will put more oxygen into our blood.

If particles get into our lungs, they can get trapped in the small pockets and damage them. This is what smoking does to the lungs. When these pockets are destroyed, we cannot get as much oxygen to the blood with each breath. We must breathe harder and our heart must pump faster. Smoking not only damages the lungs, but it wears out the heart as well.