What is thought to be the cause of collapsed alveoli?

Collapsed alveoli, or atelectasis, can occur due to several factors, primarily the obstruction of airways by mucus, foreign objects, or tumors, which prevents air from reaching the alveoli. Additionally, insufficient surfactant production, especially in premature infants, can lead to increased surface tension in the alveoli, causing them to collapse. Other contributing factors include shallow breathing, prolonged inactivity, and certain medical conditions that affect lung expansion.