Although nature seems to strive for the perfect balance between form and function, it does not always realize it. Sometimes there is a good reason :. A new study suggests that if human lungs were designed to function optimally their most important task - the exchange of oxygen and carbon dioxide between the blood and air - They'd be prone to disasters
gas exchange is the purpose of the lung. It requires several square kilometers worth of boots membranes in tiny bags and packaged in the human torso. To reach the small sacs called alveoli, where gas exchange takes place, the air must flow through a series of tubes of smaller and smaller called bronchioles.
Although necessary to provide air, bronchioles take place in the lungs that might otherwise used for gas exchange. The best design lung would seemingly find a perfect balance between the need to have fairly wide bronchioles to minimize the friction of air flow while keeping the maximum volume available for recess.
Unexpectedly, this is not what happens in our lungs, Bernard Sapoval of the Ecole Polytechnique in Palaiseau, France, and colleagues report in the February 12 issue of Nature . Our bronchioles are wider than they need to be to minimize the resistance, and the team Sapoval think they know why: security. The researchers' calculations show that if the lungs have been optimized for the exchange of gases, even a minor narrowing of a bronchiole would considerably increase the resistance to air flow - which could mean the difference between inhalation effortlessly and panting like an asthmatic. Asthma, in fact, is an excellent example of why a small excess volume does not hurt; during an asthma attack, the bronchioles constrict, making the effortful breathing. If our bronchioles started narrower, the same amount of constriction would make breathing almost impossible.
If the optimal design for gas exchange has a dangerous side effect, said Hiroko Kitaoka the University of Osaka in Osaka, Japan, perhaps Savopal and quantitative approach to his colleague can find the best compromise. It may be that nature has already found. As Sapoval said, "our lungs are built on the safe side."
Related site
website Hiroko Kitaoka
0 Komentar