| Cells cannot remain alive outside certain limits of temperature and much narrower limits mark the boundaries of effective functioning. Enzyme systems of mammals and birds are most efficient only within a narrow range around 37C; a departure of a few degrees from this value seriously impairs their functioning. Even though cells can survive wider fluctuations the integrated actions of bodily systems are impaired. Other animals have a wider tolerance for changes of bodily temperature. For centuries it has been recognized that mammals and birds differ from other animals in the way they regulate body temperature. Ways of characterizing the difference have become more accurate and meaningful over time, but popular terminology still reflects the old division into "warm-blooded" and "cold-blooded" species; warm-blooded included mammals and birds whereas all other creatures were considered cold-blooded. As more species were studied, it became evident that this classification was inadequate. A fence lizard or a desert iguana—each cold-blooded----usually has a body temperature only a degree or two below that of humans and so is not cold. Therefore the next distinction was made between animals that maintain a constant body temperature, called home0therms, and those whose body temperature varies with their environments, called poikilotherms. But this classification also proved inadequate, because among mammals there are many that vary their body temperatures during hibernation. Furthermore, many invertebrates that live in the depths of the ocean never experience change in the depths of the ocean never experience change in the chill of the deep water, and their body temperatures remain constant. | |
| 细胞只能在一定的温度范围内存活，而进一步保证它们有效工作的温度范围就更小了。哺乳动物和鸟类的酶系统只能在37℃左右的很小范围内才能有效工作。与此 相差仅几度的温度都会大大削弱它们的工作效率。尽管温度变化更大时细胞仍能存活，但机体系统的整体运行能力却被削弱了。其它动物对体温的变化有更强的适应 性。 几个世纪以来，人们就认识到哺乳动物和鸟类调节体温的方式与其它动物不同。随着时间的推移，人们对这种差异的描述越来越精确和有意义，但是"暖血动物" 和"冷血动物"这一古老的分类方式至今仍在大众词汇中有所反映。暖血动物包括哺乳动物和鸟类，其它动物统统被视为冷血动物。但是对更多物种进行的研究表明 这种分类显然是不适当的。美洲一种小型蜥蜴和沙漠鬣蜥同属冷血动物，但实际上它们的体温通常只比人类的体温低1～2度，因此并不是真正的冷血。因此又出现 了恒温动物(即保持恒定体温的动物)和变温动物(即体温随外界环境的变化而改变的动物)这一区分方式。但这种分类也不恰当。因为有不少哺乳动物在冬眠期间 会改变体温，而许多生活在深海的无脊椎动物在寒冷的深海水域中体温并不变化，而是恒定的。 |
| Cells cannot remain alive outside certain limits of temperature and much narrower limits mark the boundaries of effective functioning. Enzyme systems of mammals and birds are most efficient only within a narrow range around 37C a departure of a few degrees from this value seriously impairs their functioning. Even though cells can survive wider fluctuations the integrated actions of bodily systems are impaired. Other animals have a wider tolerance for changes of bodily temperature. For centuries it has been recognized that mammals and birds differ from other animals in the way they regulate body temperature. Ways of characterizing the difference have become more accurate and meaningful over time, but popular terminology still reflects the old division into " warmblooded" and " coldblooded" species warmblooded included mammals and birds whereas all other creatures were considered coldblooded. As more species were studied, it became evident that this classification was inadequate. A fence lizard or a desert iguana each coldbloodedusually has a body temperature only a degree or two below that of humans and so is not cold. Therefore the next distinction was made between animals that maintain a constant body temperature, called home0therms, and those whose body temperature varies with their environments, called poikilotherms. But this classification also proved inadequate, because among mammals there are many that vary their body temperatures during hibernation. Furthermore, many invertebrates that live in the depths of the ocean never experience change in the depths of the ocean never experience change in the chill of the deep water, and their body temperatures remain constant. | |
| xi bao zhi neng zai yi ding de wen du fan wei nei cun huo, er jin yi bu bao zheng ta men you xiao gong zuo de wen du fan wei jiu geng xiao le. bu ru dong wu he niao lei de mei xi tong zhi neng zai 37 zuo you de hen xiao fan wei nei cai neng you xiao gong zuo. yu ci xiang cha jin ji du de wen du dou hui da da xue ruo ta men de gong zuo xiao lv. jin guan wen du bian hua geng da shi xi bao reng neng cun huo, dan ji ti xi tong de zheng ti yun xing neng li que bei xue ruo le. qi ta dong wu dui ti wen de bian hua you geng qiang de shi ying xing. ji ge shi ji yi lai, ren men jiu ren shi dao bu ru dong wu he niao lei tiao jie ti wen de fang shi yu qi ta dong wu bu tong. sui zhe shi jian de tui yi, ren men dui zhe zhong cha yi de miao shu yue lai yue jing que he you yi yi, dan shi" nuan xue dong wu" he" leng xue dong wu" zhe yi gu lao de fen lei fang shi zhi jin reng zai da zhong ci hui zhong you suo fan ying. nuan xue dong wu bao kuo bu ru dong wu he niao lei, qi ta dong wu tong tong bei shi wei leng xue dong wu. dan shi dui geng duo wu zhong jin xing de yan jiu biao ming zhe zhong fen lei xian ran shi bu shi dang de. mei zhou yi zhong xiao xing xi yi he sha mo lie xi tong shu leng xue dong wu, dan shi ji shang ta men de ti wen tong chang zhi bi ren lei de ti wen di 1 2 du, yin ci bing bu shi zhen zheng de leng xue. yin ci you chu xian le heng wen dong wu ji bao chi heng ding ti wen de dong wu he bian wen dong wu ji ti wen sui wai jie huan jing de bian hua er gai bian de dong wu zhe yi qu fen fang shi. dan zhe zhong fen lei ye bu qia dang. yin wei you bu shao bu ru dong wu zai dong mian qi jian hui gai bian ti wen, er xu duo sheng huo zai shen hai de wu ji zhui dong wu zai han leng de shen hai shui yu zhong ti wen bing bu bian hua, er shi heng ding de. |
| Cells cannot remain alive outside certain limits of temperature and much narrower limits mark the boundaries of effective functioning. Enzyme systems of mammals and birds are most efficient only within a narrow range around 37C a departure of a few degrees from this value seriously impairs their functioning. Even though cells can survive wider fluctuations the integrated actions of bodily systems are impaired. Other animals have a wider tolerance for changes of bodily temperature. For centuries it has been recognized that mammals and birds differ from other animals in the way they regulate body temperature. Ways of characterizing the difference have become more accurate and meaningful over time, but popular terminology still reflects the old division into " warmblooded" and " coldblooded" species warmblooded included mammals and birds whereas all other creatures were considered coldblooded. As more species were studied, it became evident that this classification was inadequate. A fence lizard or a desert iguana each coldbloodedusually has a body temperature only a degree or two below that of humans and so is not cold. Therefore the next distinction was made between animals that maintain a constant body temperature, called home0therms, and those whose body temperature varies with their environments, called poikilotherms. But this classification also proved inadequate, because among mammals there are many that vary their body temperatures during hibernation. Furthermore, many invertebrates that live in the depths of the ocean never experience change in the depths of the ocean never experience change in the chill of the deep water, and their body temperatures remain constant. | |
| xì bāo zhǐ néng zài yí dìng de wēn dù fàn wéi nèi cún huó, ér jìn yī bù bǎo zhèng tā men yǒu xiào gōng zuò de wēn dù fàn wéi jiù gèng xiǎo le. bǔ rǔ dòng wù hé niǎo lèi de méi xì tǒng zhǐ néng zài 37 zuǒ yòu de hěn xiǎo fàn wéi nèi cái néng yǒu xiào gōng zuò. yǔ cǐ xiāng chà jǐn jǐ dù de wēn dù dōu huì dà dà xuē ruò tā men de gōng zuò xiào lǜ. jǐn guǎn wēn dù biàn huà gèng dà shí xì bāo réng néng cún huó, dàn jī tǐ xì tǒng de zhěng tǐ yùn xíng néng lì què bèi xuē ruò le. qí tā dòng wù duì tǐ wēn de biàn huà yǒu gèng qiáng de shì yìng xìng. jǐ gè shì jì yǐ lái, rén men jiù rèn shi dào bǔ rǔ dòng wù hé niǎo lèi tiáo jié tǐ wēn de fāng shì yǔ qí tā dòng wù bù tóng. suí zhe shí jiān de tuī yí, rén men duì zhè zhǒng chā yì de miáo shù yuè lái yuè jīng què hé yǒu yì yì, dàn shì" nuǎn xuè dòng wù" hé" lěng xuè dòng wù" zhè yī gǔ lǎo de fēn lèi fāng shì zhì jīn réng zài dà zhòng cí huì zhōng yǒu suǒ fǎn yìng. nuǎn xuè dòng wù bāo kuò bǔ rǔ dòng wù hé niǎo lèi, qí tā dòng wù tǒng tǒng bèi shì wéi lěng xuè dòng wù. dàn shì duì gèng duō wù zhǒng jìn xíng de yán jiū biǎo míng zhè zhǒng fēn lèi xiǎn rán shì bù shì dàng de. měi zhōu yī zhǒng xiǎo xíng xī yì hé shā mò liè xī tóng shǔ lěng xuè dòng wù, dàn shí jì shang tā men de tǐ wēn tōng cháng zhǐ bǐ rén lèi de tǐ wēn dī 1 2 dù, yīn cǐ bìng bú shì zhēn zhèng de lěng xuè. yīn cǐ yòu chū xiàn le héng wēn dòng wù jí bǎo chí héng dìng tǐ wēn de dòng wù hé biàn wēn dòng wù jí tǐ wēn suí wài jiè huán jìng de biàn huà ér gǎi biàn de dòng wù zhè yī qū fēn fāng shì. dàn zhè zhǒng fēn lèi yě bù qià dàng. yīn wèi yǒu bù shǎo bǔ rǔ dòng wù zài dōng mián qī jiān huì gǎi biàn tǐ wēn, ér xǔ duō shēng huó zài shēn hǎi de wú jǐ zhuī dòng wù zài hán lěng de shēn hǎi shuǐ yù zhōng tǐ wēn bìng bù biàn huà, ér shì héng dìng de. |
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