The respiratory system is the apparatus (set of organs), which enables breathing, i.e. the exchange of gases between the body and the environment. The respiratory system begins at the nose and mouth and continues through the airways and lungs. The trachea is the largest part of the airways. The trachea divides into two smaller branches, the right and left bronchus, which lead to each of the lungs (the right and left).

The pulmonary cellular system mediates the exchange of oxygen and carbon dioxide between the body and its environment. Endothelial cells, epithelial cells, smooth muscle cells and fibroblasts are essential components required for the normal functioning of the respiratory system. Abnormal proliferation and regulation of cells in the pulmonary system contribute to the development of pathological disorders such as chronic obstructive pulmonary disease, pulmonary vascular disease, asthma, oedema and lung cancer. We propose different types of normal human primary cells in the pulmonary cell system.