Atelectasis is known to do which of the following?

Atelectasis refers to the collapse or closure of a lung resulting in reduced or absent gas exchange in the affected regions. When this occurs, one of the key physiological effects is a decrease in surfactant synthesis. Surfactant is a substance composed mostly of lipids and proteins that reduces surface tension within the alveoli and is crucial for maintaining lung function.

In cases of atelectasis, the reduced surface area for gas exchange can lead to a hypoxic environment, which in turn causes the type II alveolar cells to diminish surfactant production. This is significant because surfactant helps prevent the collapse of the alveoli and ensures that they remain open during the respiratory cycle. If surfactant production is decreased, the already collapsed areas of the lung cannot expand effectively, leading to further complications in gas exchange and overall lung mechanics.

In the context of the other options, atelectasis does not enhance gas exchange or improve lung compliance; rather, it leads to poorer functioning of the lungs. It also does not lower surface tension, as the presence of adequate surfactant is essential for this function. Thus, the assertion that atelectasis decreases surfactant synthesis captures the physiological consequences of lung collapse accurately.