Static compliance increases in conditions where the lungs or arteries can expand more easily, such as in emphysema or with reduced surfactant, leading to less resistance to inflation
Static compliance will increase if there is a decrease in the elastic resistance of the lung tissues or the chest wall, allowing them to expand more easily. This may occur with conditions such as emphysema, where there is a loss of elastic tissue, or in cases where there is reduced surfactant, which normally helps to decrease the surface tension within the alveoli and makes the lungs more compliant. Conversely, static compliance decreases in conditions like fibrosis, where lung tissue becomes stiff and harder to inflate.
In the context of the vascular system, a similar concept of compliance is applied. A healthy artery with good compliance will efficiently expand as blood is pumped through it. However, in arteriosclerosis, compliance is reduced due to stiffening of the arteries, leading to increased resistance and blood pressure, as well as an increased workload for the heart. The greater compliance of a vein compared to an artery allows it to expand and hold more blood without as much increase in pressure.
In summary, static compliance increases when the lung or artery can expand more easily due to a decreased internal structural resistance, which might be due to pathological changes like emphysema or reduced elasticity of the lung tissues.