[svetliy]

I was recently reading through the "Manual" and 2 numbers caught my attention 21% and 16%, the amount of O2 in the normal air and exhaled air. I was wondering if there is any method to reduce these 16% - to make your alveoli extract the air more efficiently?and if there is a reason for their inefficient work?Does it have something to do with the fact that not all of inhaled air is used for respiration? I have read that alveolar ventilation depends on tidal volume and the rate of breathing/but what about actual respiration?