At some point in your life, you have probably encountered the statement, the mitochondria is the powerhouse of the cell. But if you don't have any idea how powerhouse works, that statement can make things more confusing. This video, we hope to illuminate that meaning for you. Here, we have a candle. For all intents and purposes, this is our powerhouse. As it burns, we can feel the heat and see the light it's releasing its energy. It's burning a wick, turning it to smoke. Our mitochondria, tiny structures found in almost all of our cells, are also burning in a sense. They are converting sugars and fatty acids into readily accessible and stored fuel called adenosine triphosphate or ATP. They, much like the candle in front of me, need oxygen to burn. When people say space is a dangerous place because there is no air, this is in part what they mean. Our whole body works to make sure oxygen can get to every single cell. From our nose and mouth, fresh air rich in oxygen travels through the pharynx and into the trachea. From there, branching paths called bronchi become bronchioles moving the air deep within our lungs. How the oxygen enters the blood is a process of pressure. We'll come back to pressure in the next video. But for now, oxygen enters the blood and is picked up by red blood cells. The newly oxygen-rich blood then travels to the heart in pulmonary veins, enters the left atrium, is passed to the left ventricle, and exits when the heart squeezes. The blood travels through arteries that branch and becomes smaller arterioles before they finally become capillaries, tiny blood vessels. Here, oxygen can easily be released to cells bringing us back to the mitochondria. Fire needs oxygen to mix with fuel as it burns. This process, known as oxidation, will see molecules made of carbon and hydrogen react with oxygen forming carbon dioxide, and surprisingly, water. When this reaction occurs, heat and light are released, allowing for the next reaction to occur, which is why fires keep growing. Our bodies are a little bit smarter. Rather than create a fire, they oxidize sugars and fatty acids to generate ATP and produce, once again, carbon dioxide and water. ATP can then be used like mini batteries, stored energy to power the rest of the cell. Finally, the carbon dioxide and water are taken back into the capillaries and mixed with the deoxygenated blood. The blood travels into venules and then veins, which all returned to the heart. From the right atrium to the right ventricle, the blood is again squeezed out of the heart this time into pulmonary arteries before returning to where it all began, capillaries in the lungs. The carbon dioxide and water will leave and be exhaled and replaced with oxygen, thus starting the cycle all over again. Now you know the basics of the pulmonary and circulatory systems, which will help us answer our questions. It's simple. When a fire is cut off from oxygen, it can no longer burn. When a human is cut off from oxygen, the fire of life dwindles before it is gone.