Pulmonary parenchyma is a term that refers to the parts of the lungs involved in gas transfer. These include the alveoli, interstitium, blood vessels, bronchi and bronchioles. The function of the parenchyma in the lungs is to exchange oxygen and carbon dioxide.
Pulmonary parenchyma is used to refer to the alveoli, which are directly responsible for the exchange of oxygen and carbon dioxide, but there are multiple functioning parts of lung tissue that make up this system. Air enters through the mouth, passes into the trachea and then into the pulmonary parenchyma, states About Health. Air enters the main bronchus and passes into tube-like bronchi in each lung. Air next enters the bronchioles, which further separate like tree branches, and finally reaches the alveolar system, which exchanges oxygen for carbon dioxide.
Lung parenchyma is susceptible to a range of diseases, which may cause increased lucency or an increase in density on a chest X-ray. As the density of lung tissue visible on an X-ray is related to the actual density of a lung, plain radiographs are used for diagnosing parenchymal lung diseases, according to Radiopaedia. Some of the pulmonary opacifications visible in parenchymal lung diseases include nodular opacifications, interstitial opacification, atelectatic opacification and airspace opacification.