If you say that you can’t live without your favourite food or beloved, you’re wrong. You’d probably have a hard time but it is really oxygen that you can’t live without. For an average person, an oxygen dearth of three mere minutes can cause irreparable brain damage and may be fatal as well. The air we breathe in consists of roughly 21 per cent oxygen. Would our lives get any better if we were to breathe in, say, a more oxygen saturated air?
Try holding your breath for some time. You’d be struggling for breath near one-minute mark given for a fact that you are no fitter than the regular couch potato. Oxygen is vital for life to go on. (Now that does not, however, apply to anaerobic organisms— organisms which do not need oxygen for survival such as, Clostridium botulinum, a bacterial species). Too little, we die and too much, we die even faster. This crazy, counterintuitive phenomenon can be termed as ‘oxygen toxicity’.
Oxygen is one of the key reactants used in respiration where glucose is oxidised to release energy in the form of ATP. So why is it that the same molecule fuelling life is also halting it? An abundance of this gas in the body triggers the generation of free radicals which are also normally formed as intermediates in biochemical reactions. Any atom, molecule or ion in possession of an unpaired electron is called a free radical. They are highly reactive chemical species. Linked to rapid aging, free radicals can react with DNA and proteins. The body has antioxidants and special enzymes to cope with their ill-effects. They can strip off an electron from one molecule turning it into a radical. This again pulls off an electron from another molecule further destabilising it. The body uses antioxidants and enzymes to counter its effects. But when they go overboard, the domino effect can lead to cellular damage or death. For instance, if the lipids in cell membrane are damaged, the selective entry and exit of substances are no longer controlled. Also, inactivation of enzymes and mutation in DNA can inhibit its replication.
Surplus oxygen is again a killer while treating patients with Chronic Obstructive Pulmonary Disease COPD. COPD is a term collectively used to refer to emphysema, chronic bronchitis and asthma. Sufferers often require supplemental oxygen at one point due to loss of lung functioning. A normal, healthy being relies on high carbon dioxide levels that stimulate the brain to breathe unlike COPD patients; they become less sensitive to carbon dioxide. So, low oxygen levels are used as an indicator instead. But, providing too much oxygen removes the stimulus to breathe and hence the removal of CO2. This results in a high blood CO2 level. The symptoms are headache, drowsiness, and confusion. In severe cases, it can lead to coma or death. Therefore, the flow rate of oxygen is set by the physician after carrying out a series of tests.
As said by American novelist, Edna Ferber, ‘Perhaps too much of everything is as bad as too little’, it is apt to explain the case of oxygen.
Hiya Islam is a student of BRAC University
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