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Gas exchange is the physical process by which gases move passively by diffusion across a surface. For example, this surface might be the air/water interface of a water body, the surface of a gas bubble in a liquid, a gas-permeable membrane, or a biological membrane that forms the boundary between an organism and its extracellular environment.
The group that includes mammals and birds, both "warm-blooded" homeothermic animals (in red) is polyphyletic.. Homeothermy, homothermy or homoiothermy [1] is thermoregulation that maintains a stable internal body temperature regardless of external influence.
Pregnancy tends to increase ventilation (lowering plasma carbon dioxide tension below normal values). This is due to increased progesterone levels and results in enhanced gas exchange in the placenta .
Gas exchange in the lungs occurs in millions of small air sacs; in mammals and reptiles, these are called alveoli, and in birds, they are known as atria. These microscopic air sacs have a very rich blood supply, thus bringing the air into close contact with the blood. [ 2 ]
Liquid breathing is a form of respiration in which a normally air-breathing organism breathes an oxygen-rich liquid which is capable of CO 2 gas exchange (such as a perfluorocarbon). [ 1 ] The liquid involved requires certain physical properties, such as respiratory gas solubility, density, viscosity, vapor pressure and lipid solubility, which ...
Gigantothermy allows animals to maintain body temperature, but is most likely detrimental to endurance and muscle power as compared with endotherms due to decreased anaerobic efficiency. [4] Mammals' bodies have roughly four times as much surface area occupied by mitochondria as reptiles, [ clarification needed ] necessitating larger energy ...
This is important because the core temperature of mammals can be controlled to be as close as possible to the optimal temperature for enzyme activity. The overall rate of an animal's metabolism increases by a factor of about two for every 10 °C (18 °F) rise in temperature, limited by the need to avoid hyperthermia. Endothermy does not provide ...
In addition to adjusting to temperature, BMR also may adjust before annual migration cycles. [7] The red knot (ssp. islandica) increases its BMR by about 40% before migrating northward. This is because of the energetic demand of long-distance flights. The increase is likely primarily due to increased mass in organs related to flight. [10]