Why do humans need to breath? Breathing is a part of the process that maintains levels of oxygen in the body. When we stop breathing, no oxygen gets to the brain, which can very quickly lead to brain damage and even death.
Breathing—though natural—is a very complex process. First, air must pass through the nose or the mouth and down through the pharynx, which is a tube in the throat. Then the trachea, which is located at the bottom of the pharynx, pushes oxygen into the lungs.
The lungs, two grayish-pink bags in the chest, are critical to respiration. While in the lungs, air passes through thin walls of the alveoli, which are tiny air sacs, into the blood cells that line the alveoli. Every time a person takes a breath, the airways in the lungs provide a huge surface area for oxygen to seep into the blood. The diaphragm flattens to pull the lungs down and draw in air. By passing oxygen from the air into blood cells, lungs help ensure that the brain has enough oxygen to function regularly. There are over 300 million alveoli working to oxygenate the blood.
Blood cells also need oxygen so that they can break down nutrients and get rid of carbon dioxide. This unwanted carbon dioxide leaves the body when you breathe out. Through this part of the process, the body also converts sugar into energy. Because this conversion creates heat, it is called “burning.”
The average human takes in a remarkable 600 million breaths during his or her lifetime. Essential to human life, the complicated respiratory system allows us to survive!
[Source: The Big Book of Knowledge]