I wondered why my fev1% was so low, yet my gas exchange is in the moderate area. Most alphas have basal emphysema which effects the lower lobe of the lung first. The gas exchange, dlco, is commonly not effected as quickly as in other emphysema types.
The gravitational pulmonary blood flow is why most alphas have basal damage. The alpha protein neutralizes the enzymes like elastase from continuing to gobble up normal lung tissue. Alphas lack enough of this protein which is produced in the liver. So I guess an elementary analogy could be scrubbing the same spot on a linoleum floor until the pattern is gone, scrubbed through. So you see the back of color of the linoleum.