Effing hampsters…let’s try this again.
Where I work (I’m a mechanical engineer) we have this in-joke; it goes like this: “All you have to do is ____. After all, how hard could it be?” This is followed by laughter, and then a sober pause when we realize that people actually think it is just that easy to cram an ICBM booster into a medium-sized cargo aircraft.
Oh, where was I? Yeah, the lung. As the OP notes, the primary purpose of the lung is rather straightforward: to exchange waste carbon dioxide with fresh diatomic oxygen, which is transported by hemoglobin to the cells for use in the Krebs cycle. The specific mechanisms by which it does so, on the other hand, are very intricate. If the heart is a pump, the lungs are a refinery with stage after stage of fractionalization columns and distillation reactors. The lungs essentially take arterial blood and run it through successively finder capillaries until it runs through alveoli, which are little sacs that are thin enough to allow oxygen (and other air gases) in, while preventing the blood from spilling out or clotting up. Developing such organs was a major evolutionary stepping stone which allowed vertebrates to emerge from the thick, oxygenated fluid of the oceans into the tenuous, dangerously thin atmosphere and still absorb enough life-giving oxygen to make living worthwhile, and moreover, to feed the incredibly oxygen-greedy brains of primates.
The lungs are also, by nature of what they do, a very delicate organ; while treating them properly requires little maintanence for a lifetime of reliable function, subjecting them to inhaled toxicants, vaporous solvents, or sudden pressure changes can result in traumatic emphysema or other barotraumas, while regular exposure to even low levels of carcenogenic compounds or surfectant-destroying compounds (like those found in tobacco smoke) can cause various problems leading to chronic emphysema. Creating an artifical version that works as well while tolerating abuse that natural lungs without maintanence will is an enormous feat of biomedical engineering indeed.
There are machines that do this–the heart-lung machine that is regularly used in open-heart surgery to replace the temporarily bypassed heart–but as you can see from the picture these are large, complex machines that require expert monitoring. There is some research into implantable artificial lungs, but the machines are obviously far from perfect. In any case, implanted artificial organs are far from a mature field, suffering from high rates of infection, rejection reactions by surrounding tissue, and malfuction.
The lungs also perform some ancillary actions, such as releasing hormones that control blood consistancy, and of course they’re strongly tied into the most primitive parts of the brain as a primary member in the respiration system, so even relegating them to the job description of “air filter” is unfairly diminishing their complexity. The lungs may perform a “simple” job, but the structure that lets them do this is intricate indeed.
Stranger
