How Humans Breathe

You need to get oxygen from the air into your bloodstream so that it can get to your cells for respiration. You also need to get rid of carbon dioxide in your blood. This happens inside the lungs. Breathing is how the air gets in and out of your lungs. Breathing in involves the intercostal muscles and diaphragm to contract, the Thorax (upper part of the body) volume to increase and a decrease is pressure drawing air in. In contrast breathing out involves the intercostal muscles and diaphragm to relax, the Thorax to decrease in volume and therefore air is forced out. Lungs are like sponges in our Thorax - protected by the ribcage. The air breathed in goes down your Trachea (windpipe) then splits into two tubes called Bronchi, each one going into a lung. Then the Bronchi split into smaller tubes called Bronchioles - which finally lead to small air sacs called Alveoli where the gase exchange of carbon dioxide and oxygen takes place.