During gas exchange, the cell membrane of a single-celled organism has the same function as the respiratory system in humans. The respiratory system is a biological system which is composed of specific organs and structures such as nose, pharynx, larynx, trachea, bronchi and lungs that are used for gas exchange in humans. The primary function of the respiratory system is to transport oxygen into the body and to breathe out carbon dioxide, which is a waste product of cellular function
Cutaneous membrane also known as the skin
The diaphragm contracts and the thoracic cavity increases in volume. It decreases the intraalveolar pressure so that air flows into the lungs.