Final answer:
Lung compliance is decreased in restrictive lung diseases such as respiratory distress syndrome, where the airways become stiff, and when intra-alveolar pressure is increased, not when there is an excess of pulmonary surfactant.
Step-by-step explanation:
Lung compliance is a measure of the lung's ability to stretch and expand. It is decreased in restrictive lung diseases where the airways are less compliant and become fibrotic or stiff. Decreased compliance means that the lung tissue cannot easily bend and move, making it more difficult for air to be exhaled. This is seen in illnesses like respiratory distress syndrome and pulmonary fibrosis. In these conditions, the intrapleural pressure becomes more positive, causing the airways to collapse upon exhalation and trapping air in the lungs.
Lung compliance is also compromised when intra-alveolar pressure increases, as it impedes the lungs' ability to expand during breathing. However, if there is too much pulmonary surfactant, this typically would increase the compliance of the lung, making it easier for the lungs to expand. Surfactant decreases the surface tension within the alveoli, normally aiding the lungs to inflate more readily.
Thus, the correct answer to the question is:
- f) Answers b and c are correct.