When we think about oxygen? Then, when it is not enough. Let's not wait for this unpleasant moment and remember it now. Thus, oxygen – 8-th element of the periodic table (the nuclear charge of 8), chemical symbol – O, relative atomic mass (atomic weight) – 16. The valence of oxygen in compounds is two, the most common oxidation state of -2. Oxygen molecule O 2, molecular weight (MW) – 32 amu Well, it is for lovers of all chemistry, we are also the question of the oxygen of interest and concern is quite another.
Namely, that the oxygen in the air constantly occur two processes: its completion and its disappearance. Over the completion worked tirelessly oxygen photosynthesis of green plants, photochemical decomposition of water vapor in the upper atmosphere and activity of phytoplankton the oceans and seas. For what they have to thank you very much. But on the other hand, various achievements of civilization successfully degrade both qualitative and quantitative replenishment of oxygen in the atmosphere. Lack Without food a person can do for weeks, without water – for days, but without oxygen within minutes, most cells in our body dies. Oxygen is used in humans for most of the redox reactions that result in produces the energy required for vital processes. If you violate the mechanism of oxygen to the body or processes of transport it is developing anoxia – hypoxia.
Most sensitive to lack of oxygen are the cells of the central nervous system. Our wise central nervous system, sensing something was wrong, gives a command to all organs and body systems: an urgent rectify the situation – as a consequence increases blood pressure in the circulatory system and heart rate accelerates. You can check this for yourself (carefully): hold your breath for the maximum possible time, and you feel the heart beat furiously begins.