Final answer:
A decrease in surfactant causing alveolar collapse is known as Atelectasis, which is distinguished from other respiratory conditions such as Emphysema, where alveoli walls are destroyed; Asthma, which involves airway obstruction; and Pulmonary fibrosis, where lungs become less pliable.
Step-by-step explanation:
A decrease in surfactant causing the alveoli to collapse is called Atelectasis. Surfactant is a substance that helps to reduce surface tension in the alveoli, the tiny air sacs in the lungs, and prevents them from collapsing. When there is a decrease in surfactant, the alveoli are more likely to collapse, leading to atelectasis. This condition differs from Emphysema where the alveolar walls are destroyed, decreasing the surface area for gas exchange, and from Asthma, which involves airway obstruction due to inflammation. In Pulmonary fibrosis, the lungs become less pliable due to scarring. Therefore, proper pulmonary ventilation is compromised. Atelectasis can be associated with a decrease in volume that leads to increased resistance to airflow and difficulty with ventilation.