Respiration is the act of breathing in and out. When you breathe in, you take in oxygen. When you breathe out, you give off carbon dioxide.
The respiratory system is made up of the organs involved in the interchanges of gases:
Voice box (larynx)
The upper respiratory tract includes the:
Air-filled space above and behind the nose (nasal cavity)
The lower respiratory tract includes the:
Air sacs (alveoli)
The lungs take in oxygen. The body's cells need oxygen to live and carry out their normal functions. They also get rid of carbon dioxide. This is a waste product of the cells.
The lungs are two cone-shaped organs. They're made up of spongy, pinkish-gray tissue. They take up most of the space in the chest, or the thorax (the part of the body between the base of the neck and diaphragm). They're inside a membrane called the pleura.
The lungs are separated by an area (mediastinum) that has:
Heart and its large vessels
Food pipe (esophagus)
The right lung has three lobes. The left lung has two lobes. When you breathe, the air:
Enters the body through the nose or mouth
Travels down the throat through the voice box and windpipe
Goes into the lungs through tubes (mainstem bronchi):
One of these tubes goes to the right lung and one goes to the left lung
In the lungs, these tubes divide into smaller bronchi
Then into even smaller tubes called bronchioles
Bronchioles end in tiny air sacs called alveoli
An important part of a baby's lung development is the production of surfactant. This is a substance made by the cells in the small airways. By about 35 weeks of pregnancy, most babies have developed enough surfactant. It's normally released into the lung tissues. There it helps to keep the air sacs open. Premature babies may not have enough surfactant in their lungs. They may have trouble breathing.