I have an anatomy textbook that states
“when actively contracting, each thick filament (in a muscle fiber) breaks down roughly 2500 ATP molecules per second. …Because even small skelatl muscles contains thousands of muscle fibers, the ATP demands of contracting skeletal muscles are enormous. In practical terms, the demand for ATP in a contracting muscle fiber is so high that it would be impossible to have all the necessary energy available as ATP before the contraction begins.”
So here is my question. What exactly is the role of Oxygen in human energy production? The human body is apparently able to store enough sugar to stay alive for weeks without additional food, but it can’t store enough Oxygen? I don’t seem to be able to find an explanation for this clear enough to penetrate my thick head. Does the human body use 10000 times more oxygen in its chemical processes for generating energy than sugar?
How do you think you will be able to store the oxygen? All you can do is dissolve the stuff in water, and it’s pretty difficult to do that compared to even, say, sugar! Sugars, in contrast, can polymerize, undergo various chemical changes, make 'em fats, stack 'em up, stretch 'em out, float ‘em around… basically they can go into all sorts of alternative configurations to be stored for a long period. You realize, of course, that the oxygen is needed for the combustion that is the ultimate sources of our energy (even though ATP to ADP is what is commonly quoted, it is the burning to oxides that is ultimately the energy source we rely upon.) You need both the combustible material and the oxygen in to get the stuff working and you just can’t dissolve enough oxygen in your blood using just one breath and then twiddlin’ your thumbs for a few days.
Why is oxygen so hard to dissolve? Because it’s pretty much a happy non-polar gas molecule. Why it dissolves at all has to do with partial pressures and statistical mechanics. The gist is basically that you inhale a lot more gas than you can get dissolved into your bloodstream… and once it gets depleated, the partial pressure drops and not as much can get redissolved (that’s why it’s a bad idea to rebreathe your own recirculated breath).
If your interested more in this stuff, I suggest a intro chemistry text. Look up combustion and dissolution of gases. That should just about do it.