Homoiothermy — a new stage of evolution. It gave an animal a chance to survive in the conditions of different climate and to be active both during a heat, and during cold. But the high power consumption which can lead to death became payment for new qualities. Nevertheless natural selection took the part of homoiothermy. And the person — a nature wreath — is the representative of warm-blooded mammals.
Instruction
1. Warm-blooded (gomoyotermny) animals are capable to maintain constant body temperature, irrespective of ambient temperature. Mammals, including the person, and birds treat such animals.
2. Temperature of warm-blooded is rather constant. Birds it usually 40 — 43 °C, at mammals — 38 — 40 °C, at the person have 36.6 — 36.9 °C. The echidna and a duck-bill — the lowest of mammals — show the greatest temperature changes. According to different data, temperature of bodies of these animals can stay within 22 — 36 °C. And at the animals falling into hibernation, body temperature is much lower during sleep, than during wakefulness.
3. Homoiothermy became possible thanks to thermal control processes. At air fall of temperature the organism of gomoyotermny animals strengthens formation of heat due to autonomous power generation from the received food. At the same time the organism shows the high level of metabolism. Means, it costs at the following step of development, in comparison with cold blooded.
4. It is very important to keep the developed heat. Here the ability of skin to change of heat conductivity by expansion and narrowing of her blood vessels enters work. Fur of animals, feathers of birds, indumentum of the person create a layer of air around a body and reduce return of heat outside. The layer of subcutaneous fat also promotes heat preservation. A body shiver when the person or an animal freezes — too a way of maintenance of the necessary body temperature. Heat generation increases also during increase in physical activity.
5. On the other hand, to avoid overheating of an organism, there is a sweating mechanism. Thus the body is cooled. Also behavioural thermal control is not less important. In cold season the living being looks for the place warmer, and during a heat both the person, and an animal, and a bird look for a shady place.
6. Warm-blooded animals can live in territories with very frigid climate and to be active at sharp jumps of temperature. But on cold they spend bigger amount of energy for temperature maintenance of a body and consequently, they need a lot of food. Here also the homoiothermy defect is only, perhaps. If at a low temperature the insufficient quantity of food is observed, the animal is doomed to death.
7. The long time was considered to be that all mammals treat warm-blooded. But not so long ago scientists found out what among mammals is also cold blooded is a naked navvy. Body temperature of this animal depends on air temperature, as at cold blooded.
8. The question of whether there were warm-blooded dinosaurs remains a riddle. It is quite possible that these giants had constant body temperature thanks to warm climate and the large size. Possibly, inertial homoiothermy also turned a dinosaur into the tsar of the mesozoic period.