Respiration and the Respiratory System

The means by which the body takes in the oxygen during mild hyperbaric oxygen therapy is the same means through which it regularly takes in oxygen: the respiratory system. As such, in order to understand mild hyperbaric oxygen therapy, it is important to understand the complexities of the respiratory system.

The human respiratory system is a series of organs responsible for taking in oxygen and expelling carbon dioxide. This is called respiration.

Respiration is achieved through the mouth, nose, trachea, lungs, and diaphragm. Oxygen enters the respiratory system through the mouth and the nose. The oxygen then passes through the larynx and the trachea.

In the chest cavity, the trachea splits into two smaller tubes called the “bronchi.” Each bronchus then divides again, forming the bronchial tubes. The bronchial tubes lead directly into the lungs, where they divide into many smaller tubes that connect to tiny sacs called “alveoli.” The exchange of oxygen into and carbon dioxide out of the bloodstream occurs in the alveoli.

The average adult's lungs contain about 600 million alveoli, which are surrounded by capillaries. The alveolar walls are extremely thin—only about 0.2 micrometers. These walls are composed of a single layer of epithelial cells and the pulmonary capillaries. The inhaled oxygen passes into the alveoli and then diffuses through the capillaries into the arterial blood. Meanwhile, the waste-rich blood from the veins releases its carbon dioxide into the alveoli. When a person exhales, the carbon dioxide follows the same path out of the lungs that the oxygen followed entering.

Another major structure in the respiratory system is the diaphragm. The diaphragm pulls oxygen into the lungs and pumps carbon dioxide out. The diaphragm is a sheet of muscles that lies across the bottom of the chest cavity. Breathing takes place as the diaphragm contracts and relaxes. When the diaphragm contracts, oxygen is pulled into the lungs. When the diaphragm relaxes, carbon dioxide is pumped out of the lungs.

In humans, the average rate of breathing is dependent upon age. Newborns up to 6 weeks take 30 to 60 breaths per minute, while the average resting respiratory rate for adults is 12 to 20 breaths per minute. Physical exertion also has an impact on respiratory rate, and healthy adults can average 45 breaths per minute during strenuous exercise.