Lungs
Definition: The lungs are part of the respiratory system. The lungs are large, conical-shaped, lobed organs located in the chest behind the ribcage. The lungs are composed of a spongy, porous, elastic tissue. The right lung has three lobes, while the left lung only has two. Each lung is between 10 to 12 inches long, and are separated by the mediastinum.
The lungs are where respiration takes place. The alveoli, located within the lungs, exchange oxygen with the blood for carbon dioxide. The diaphragm and intercostal muscles, which surround the lungs, contract and relax to draw in and expel air from the lungs.
The lungs are lined with pleura, which produces surfactant to facilitate smooth movement of the lungs within the chest cavity.
The lungs have three important roles:
# Supply oxygen to the blood
# Remove wastes and toxins from the body
# Defend against hostile intruders
There are three dozen distinct cells types within the lungs, all with different responsibilities.
