Final answer:
a. Decreased lung compliance
Elderly lungs are more prone to small airway collapse due to reduced chest wall compliance and decreased lung elasticity, leading to increased resistance in the airways and difficulty in breathing.
Step-by-step explanation:
Elderly lungs are more prone to small airway collapse primarily due to reduced chest wall compliance. As people age, their lung tissue becomes less elastic, and their chest walls become stiffer. This process increases the overall resistance within the airways, making it harder for air to flow through. Consequently, lung compliance decreases, the lungs stiffen, and the airways are more susceptible to collapsing upon exhalation. Conditions such as restrictive diseases like fibrosis exemplify this by stiffening the airways and causing air to become trapped in the lungs. Similarly, an increase in resistance, seen in conditions like asthma or emphysema, can lead to difficulty in breathing due to obstructed airways and trapped air.
Lung resistance and compliance are crucial in pulmonary diseases which can affect the rate of gas exchange, impacting the ability to take in oxygen and release carbon dioxide. The elderly may experience increased physiological dead space as well, which refers to areas of the lungs that are ventilated but not well perfused, further reducing efficient gas exchange.