Combatting Oxygen Shortages
Animal kingdom emerged on our planet when the atmosphere was still very poor in oxygen. It is no wonder that living organisms had to adapt themselves to an environment where oxygen was in short supply. However, we usually fail to notice another much more puzzling phenomenon, namely, that animals living in the presence of excessive oxygen have managed to restrain the intensity of the oxidation processes taking place in their bodies as if they were always ready to extinguish a constantly threatening fire.
The amount of environmental oxygen is constant, and, if it does alter, it decreases. This explains why animals have different means of combatting oxygen shortages, but no means of protection against excess oxygen.
Paul Bert was the first to discover that breathing pure oxygen can be poisonous around a hundred years ago. This was such an unexpected discovery that scientists did not believe him and a suspicion arose that the oxygen used by Bert contained various poisonous admixtures. The experiments were repeated many times, but no matter how thoroughly the oxygen was purified, the animals which breathed it for prolonged periods inevitably perished.
Filed under oxygen | Tags: animals, breathing, oxidation, oxygen, oxygen shortage | Comment (0)Oxygen Reqiured for Muscles
Larger amounts of oxygen are required for some organs, mainly muscles, many of which work rhythmically for several hours on end. These are the muscles in the legs and wings, and the masticatory muscles, while the respiratory and cardiac muscles never cease working. It has been proved that they, cannot be supplied with oxygen while they are working for, when a muscle contracts making the vessels constrict, blood cannot flow through them.
The muscles use the oxygen stored for them by means of a special muscle hemoglobin. It is very similar to blood hemoglobin, the essential difference being that the muscle hemoglobin is much better at trapping and retaining oxygen, releasing it only when the oxygen level in the environment is very low. The cardiac muscle of a warm-blooded animal contains 0.5 per cent muscle haemoglobin, which allows two cubic centimetres of oxygen to be stored for each gram of muscle. This is quite sufficient to ensure normal functioning of the muscle for the time the blood flow is arrested.
Water mammals and waterfowl which have to stay underwater for long periods of time have converted their muscles, primarily the most important ones, to still larger stores of oxygen by saturating them with large amounts of muscle haemoglobin. This is how the sperm-whale can remain submerged for 30 to 50 minutes and swim long distances during that time. An alligator can stay in water even longer, one and a half to two hours.
Filed under oxygen | Tags: animals, blood, haemoglobin, muscles, oxygen | Comment (0)