The respiratory membrane, also called the respiratory surface, is made of the alveolar epithelial cell and the pulmonary capillary endothelial cell, and this structure helps exchange the gases of carbon dioxide and oxygen. The respiratory membrane plays a key role in exchanging gases within the lungs. This membrane also helps bring oxygen into blood and remove carbon dioxide.
The respiratory membrane contains a large surface area that is covered by thousands of smaller cell structures called alveoli. The large and permeable surface of the respiratory membrane makes it well suited for facilitating the exchange of gases that are produced and used for vital functions, such as respiration and metabolism. Gas exchange is a critical part of allowing bodies to function properly. Humans consume large quantities of oxygen, which is used by cells to produce energy and carry out basic tasks. The use of oxygen ultimately produces a waste product in the form of carbon dioxide, which must be expelled to avoid building up in the body. The respiratory membrane allows for the seamless transition of oxygen and carbon dioxide particles across its surface, as it is smooth and thin, and requires the gases to travel very short distances. Having a short travel time allows for a faster, more energy-efficient exchange of gases.