Final answer:
The term atelectasis refers to collapsed and airless alveoli, which can occur due to blockages or external pressure on the lungs causing reduced gas exchange, and is a common complication after surgery or from lung diseases such as pneumonia.
Step-by-step explanation:
The term atelectasis refers to collapsed and airless alveoli. This condition can occur as a common postoperative complication or as a result of certain lung conditions such as pneumonia and lung cancer. Atelectasis is different from a spontaneous pneumothorax, which is a collapsed lung often related to connective tissue abnormalities. Instead, atelectasis is characterized by the inability of the alveoli to expand and fill with air, thereby reducing gas exchange. Conditions that can lead to atelectasis include blockages of the air passages or pressure from outside the lung. In the context of pneumonia, the alveoli become filled with fluid, which can also impair their function. Chronic obstructive pulmonary disease (COPD), emphysema in particular, is a condition where the walls of the alveoli break down, greatly reducing the lung's ability to exchange gas and leading to symptoms similar to atelectasis such as shortness of breath.