Apologies if this has already been asked before, but it struck me today that I don’t know the answer to this and I couldn’t find it after trying to look it up.
Could anybody explain why warm-blooded animals, like humans, need to stay warm to survive? It looks like death by hypothermia is caused by the body desperately trying to maintain core temperature, but why is that so important in the first place? It’s not like you’re at risk of your blood freezing in your veins, so I’m puzzled. I’d be super grateful if anybody could explain why maintaining body temperature is so critical!
In: Biology
A body needs metabolism to work. Metabolism is nothing more than a lot of (bio-)chemical reactions. Unfortunately, many of the invoved chemical componds (especially the enzymes) only work in a verly limited range of temperature. If the temperature is too low, they simply do not work. If the temperature is too high, they are even destroyed (like e.g. an egg that gets hard when it is boiled).
This basically applies for both warm-blooded and cold-blooded creatures. Warm-blooded animals, however, have the possibility to regulate their body temperature. This makes them somewhat independent of the surrounding temperature, while cold-blooded animals either need to live in an environment that is generally warm enough, or need to actively search for warm places to get their bodies to “operating temperature”. Therefore you will not find cold-blooded animals in the arctic regions.
Edit: Warm-blooded animals are named this way, because they can keep their body temperature warm, not because they “need” warm blood. If you are sweating, they body tries to cool down. If you are shivering, the body tries to warm up. Cold-blooded animals always have the body temperature matching the surrounding temperature. Therefore “cold-blooded” is somewhat misleading,
Tissue does actually freeze in extreme cold. Blood, warmed by the chemical activity in the body distributes heat to keep that from happening, yes?
Warmth allows the chemical reactions that power our muscles to work more efficiently. A cold-blooded animal needs to warm up in the sun before they can move fast, otherwise they are very sluggish and can’t catch food. Many warm blooded animals have evolved to always have enough warmth to move and have lost the ability to function at too low a temperature. Eventually thing will happen like the heart muscle too weak to be able to pump enough blood and other organs will fail. Some animals have the ability to husband what resources they manage to build up and can slow their metabolism to operate at lower body temperatures by hibernating, we can’t.
Warm-blooded living organisms (more correctly called endothermal) have evolved to have very fast metabolism that allows for incredible features compared to ectothermal (“cold-blooded”) beings, such as being able to be fully active at any time and perform tiring efforts, like running, for prolonged times.
All of this is possible because chemical reactions producing energy, in the form of ATP molecules, happen very fast in these organisms, but this is only possible if enzymes work at the optimal temperature, which lies around 35-40°C. So these animals must keep their temperature constant in order to sustain their living functions.
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