chemical principles exemplified High Altitude Acclimatization Illustrating principles of chemical equilibrium
Infornzation provided by David E. Bass, 1J.S. Army Researcl~Institute of Environmental Medicine Suggestions front Robert E. Heme, American Chemical Sociely and Lawenee E. Shong, Earlham College A human bciug living under a particular set of environmental conditions is different, chemically, from his counterpart in a different environment! One of the most dramatic manifestations of t,his occurs when people experience rapid chmges in altitude; e.g., one flies to Aspen or the Rocky hlountain National P:uk or the Tetons for a vacat,ion and finds that at an increae in altitude to 13,000 ft the body just does not function properly-headaches, apathy, a pounding heart, gasping for breath, and nausea are common. I t is called acute mountain sickness. Alt,hough common for the tourist it is obviously more than just a minor discomfort to the athlete going to Mexico City for the Olympic games or the Indian soldier moving into t,he Himalayas to defend a border. Transport of oxygen to the musclcs ti~kesplace by oxygenation of hemoglobin in the lungs and subsequent transport of t,he oxyhemoglobin to t,he tissue. If the equilibrium in the lungs does not provide a high enough O&)
to total hemoglobin as is possible at. sea-level pressure. The body has several expedient corrective measures to relieve the discomfort and expedide the oxygen t,ransport,' but the long-term solution which nature provides is the obvious oue from consideration of chemical equilibrium. I n order to maintai~it>hedesirable concentration of oxyhcmoglohin in the blood in the presence of the decreased partial pressure of oxygeu in the lungs, the concentration of hemoglobin in the blood must increase. It takes txvo to four weeks, but this is just the \wg the body reestablishes the equilibrium. This is sho\vu by hemutocrit levels (i.e., the per cent of the hloocl volu~ne which is red cells) for long term residents :it different, altitudes, recorded in the table. These figures are not correct,ed for other environmental or sociological vnriables. Hematocrit Levels for Long Term Residents at Different Altitudes
Lima, Peru Jlenver, Colorado Mexico City Morocoeha, Pern
,512 5,280 7,460 14,.500
0.20 0.17 0.15 0.12
4546
48 51 59. ,5
+ I l b = HbOn
ratio of HbOl t,o total hemoglobin (called by biochemists the degree of saturation) to meet the demands of the tissues for 02,signals are sent t,o t,he respiratory control center in the bmin, thence to the lungs and one breathes more rapidly. But here is the problem, which is purely one of chemical equilibrium. The partial pressure of oxygen in the air at 13,000 ft is only 0.12 atm compared to 0.20 atm at sea level and, no matter how rapidly we breathe, the blood cannot att,ain as high a ratio of HbOr The exempla are designed to show fundamental chemical principlesin aperntion. They deal with phenomena in whichstuden1.s have intrinsic interest; they apply abstract ideas lo easily visualized situations. All of us have our pet anecdotes and illnstra1,iorw which we know will nt.tract the students' interest. Your cont,ribubions and suggestions are invikd. They may be sent to the author. "Biomedicine Problems of High Terrestrial Elevnlions," Symposinm, Oct. 1967. U S . Army Icesearch Iostihtte of Environmental Mediciue, Naiick, Mass. Mew Scicnlisl, July 23, 1970, p. 177. "The E k c t s of Altitude on Physical Performance," Athletic Institute, 1967.
Pop! Goes the Champagne Bottle Cork Illustrating the thermodynamics of an adiabatic expansion
Contribution by Russell Butt, K e q o n College You have probahly noted th:~t for a few moments after a bottle of beer or carbonated sotla h;:s bern opened, wisps of fog appear in the neck and just &hove the mouth of the bottle. The effect is rsprci:dly notieeal>le d ~ e na champagne bottle cork is popped, and it can be seeu wit,h calls of hever,zge as ~ w l l . Whnt. goes on hew? What is thr t~lirrmodyrlamicrxpl:~n:rtion for t,he formation of this fog? Init,ially, of course, t,he bcvcmgc hot,tlc is pressurized with a mixture of air :tnd COa, sat,uratcd wit11 watrr vapor. When t,he pressure sc:ll is brolm~,the pressurized gas undergoes a mpicl, irrwersihk rxpnusion against the atmospheric pressure. The exp:msion is so rapid as to he, to a first :rpproxirn:rtion, adinhatic, consequently the temperature decreases and some of the wat,er vapor condeuscs t,o form the ohservrd fog. Volume 48, Number 1, Januory 1971
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