Respiration is the act of breathing in and out. When you inhale, you take in oxygen. When you exhale, you give off carbon dioxide.
The respiratory system is made up of the organs involved in the interchanges of gases and consists of the:
Mouth (oral cavity)
Voice box (larynx)
The upper respiratory tract includes the:
The lower respiratory tract includes the:
Airways (bronchi and bronchioles)
Air sacs (alveoli)
The lungs take in oxygen, which the body's cells need to live and carry out their normal functions. They also get rid of carbon dioxide, a waste product of the cells.
The lungs are a pair of cone-shaped organs 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 are enveloped in a membrane called the pleura.
The lungs are separated from each other by the mediastinum, an area that contains the following:
Heart and its large vessels
The right lung has 3 lobes. The left lung has 2 lobes. When you breathe, the air:
Enters the body through the nose or the mouth
Travels down the throat through the voice box (larynx) and windpipe
Goes into the lungs through tubes called mainstem bronchi:
One mainstem bronchus leads to the right lung and one to the left lung
In the lungs, the mainstem bronchi divide into smaller bronchi
Then into even smaller tubes called bronchioles
Bronchioles end in tiny air sacs called alveoli
An important part of lung development in babies is the production of surfactant. This is a substance made by the cells in the small airways and consists of phospholipids and protein. By about 35 weeks gestation, most babies have developed enough surfactant. Surfactant is normally released into the lung tissues where it helps lower surface tension in the airways. This helps keep the lung alveoli (air sacs) open. Premature babies may not have enough surfactant in their lungs and may have difficulty breathing.