LungLungs are sacks of tissue located just below the rib cage and above the diaphragm. They are an important part of the respiratory system and waste management for the bodyThough breathing seems simple, it is a very complex process.The right lung is divided into three different sections, called lobes. The left lung has just two lobes. The lobes are made of sponge-like tissue that is surrounded by a membrane called pleura, which separates the lungs from the chest wall. Each lung half has its own pleura sack. This is why, when one lung is punctured, the other can go on working. The lungs are like bellows. When they expand, they pull air into the body. When they compress, they expel carbon dioxide, a waste gas that bodies produce. Lungs do not have muscles to pump air in and out, though. The diaphragm and rib cage essentially pump the lungs.As a person breathes, air travels down the throat and into the trachea, also known as the windpipe. The trachea divides into smaller passages called the bronchial tubes. The bronchial tubes go into each lung. The bronchial tubes branch out into smaller subdivisions throughout each side of the lung. The smallest branches are called bronchioles and each bronchiole has an air sac, also called alveoli. There are around 480 million alveoli in the human lungs, according to the Department of Anatomy of the University of Göttingen.The alveoli have many capillary veins in their walls. Oxygen passes through the alveoli, into the capillaries and into the blood. It is carried to the heart and then pumped throughout the body to the tissues and organs.As oxygen is going into the bloodstream, carbon dioxide passes from the blood into the alveoli and then makes its journey out of the body. This process is called gas exchange. When a person breathes shallowly, carbon dioxide accumulates inside the body. This accumulation causes yawning, according to York University. The lungs have a special way to protect themselves. Cilia, which look like a coating of very small hairs, line the bronchial tubes. The cilia wave back and forth spreading mucus into the throat so that it can be dispelled by the body. Mucus cleans out the lungs and rids them of dust, germs and any other unwanted items that may end up in the lungs.