Respiration is the act of breathing:
Inhaling (inspiration). Taking in oxygen.
Exhaling (expiration). Giving off carbon dioxide.
The respiratory system is made up of the organs involved in the interchanges of gases and consists of the:
Nose
Mouth (oral cavity)
Pharynx (throat)
Larynx (voice box)
Trachea (windpipe)
Bronchi
Lungs
The upper respiratory tract includes the:
Nose
Nasal cavity
Ethmoidal air cells
Frontal sinuses
Maxillary sinus
Sphenoidal sinus
The lower respiratory tract includes the:
Larynx
Trachea
Lungs
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. The lungs 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).
The lungs 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
Trachea (windpipe)
Esophagus
Thymus
Lymph nodes
The right lung has three sections, called lobes. The left lung has two lobes. When you breathe, the air:
Enters the body through the nose or the mouth.
Travels down the throat through the larynx (voice box) and trachea (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 adequate amounts of 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.
