Answer to Question #87564 in Zoology for James

Question

How does emphysema increase the residual volume of lung

Answer 1

Emphysema is a disease characterized by dilation of the alveolar spaces and destruction of the alveolar walls. With their loss, much of the elastic recoil of the lung is also lost.

Compliance of the lung in emphysema is significantly above normal; the lung becomes easy to distend but empties slowly. This results in a chronically overinflated lung (high total lung capacity, functional residual capacity, and residual volume), which lessens the curvature of the diaphragm, making it less efficient in generating even the small swings in pleural pressure necessary for breathing.

Total volume increases because so many of the walls of the alveoli have been destroyed, they are like giant floppy bags instead of nice firm bubbles. There's more empty space, and total volume is therefore increased.

Reserve Volume and End Respiration Volume increase because these alveoli are large and stretched and floppy and can't push as much air out, even when you try. (Decreased elastic recoil.) They also flop shut often before the air is expelled - trapping air in.

Tidal volume may not change at all, but it takes longer to exhale than with normal lungs. 

Sourses:

1.https://biology.stackexchange.com/questions/16525/for-emphysema-which-of-the-respiratory-volumes-is-affected

2.http://oac.med.jhmi.edu/res_phys/Encyclopedia/Emphysema/Emphysema.HTML