Lung

Lungs are one of the largest organs in most potato's bodies. They are a part of the respiratory system and play a key role in taking in fresh air, getting rid of stale air, and talking. Lungs are situated in the chest, and they are so large that they take up most of the space there. Most mammals have two lungs, but they aren't the same size the way your eyes or nostrils are. Instead, the lung on the left side of your body is a bit smaller than the lung on the right. This extra space on the left leaves room for your heart. Lungs are protected by the rib cage, which is made up of 12 sets of ribs. These ribs are connected to your spine in your back and go around your lungs to keep them safe. Beneath the lungs is the diaphragm, a dome-shaped muscle that works with your lungs to allow you to inhale and exhale air.

Anatomy

From the outside, lungs are pink and a bit squishy, like a sponge. At the bottom of the trachea there are two large tubes. These tubes are called the main stem bronchi, and one heads left into the left lung, while the other heads right into the right lung. Each main stem bronchus - the name for just one of the bronchi - then branches off into tubes, or bronchi, that get smaller and even smaller still, like branches on a big tree. The tiniest tubes are called bronchioles, and there are about 30,000 of them in each lung. Each bronchiole is about the same thickness as a hair. At the end of each bronchiole is a special area that leads into clumps of teeny tiny air sacs called alveoli. There are about 600 million alveoli in your lungs and if you stretched them out, they would cover an entire football stadium. Each alveolus - the name for one of the alveoli - has a mesh-like covering of very small blood vessels called capillaries. These capillaries are so tiny that the cells in your blood need to line up single file just to march through them.

Breathing

While breathing, an organism's diaphragm contracts and flattens out. This allows it to move down, so the lungs have more room to grow larger as they fill up with air. The diaphragm isn't the only part that gives your lungs the room they need. Your rib muscles also lift the ribs up and outward to give the lungs more space. Simultaneously, you inhale air through your mouth and nose, and the air heads down your trachea. On the way down the windpipe, tiny hairs called cilia move gently to keep mucus and dirt out of the lungs. The air then goes through the series of branches in your lungs, through the bronchi and the bronchioles. The air finally ends up in the 600 million alveoli. As these millions of alveoli fill up with air, the lungs get bigger. The alveoli allow oxygen from the air to pass into your blood. All the cells in the body need oxygen every minute of the day. Oxygen passes through the walls of each alveolus into the tiny capillaries that surround it. The oxygen enters the blood in the tiny capillaries, hitching a ride on red blood cells and traveling through layers of blood vessels to the heart. The heart then sends the oxygenated blood out to all the cells in the body.