Mandarin language learning HK – Cells and Temperature

Mandarin Lesson

Cells and Temperature

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 homeotherms, 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.

 

細胞與溫度

細胞只能在一定的溫度範圍內存活,而進一步保證它們有效工作的溫度範圍就更小了。哺乳動物和鳥類的酶系統只能在37℃左右的很小範圍內才能有效工作。與此相差僅幾度的溫度都會大大削弱它們的工作效率。儘管溫度變化更大時細胞仍能存活,但機體系統的整體運行能力卻被削弱了。其它動物對體溫的變化有更強的適應性。

幾個世紀以來,人們就認識到哺乳動物和鳥類調節體溫的方式與其它動物不同。隨著時間的推移,人們對這種差異的描述越來越精確和有意義,但是”暖血動物” 和”冷血動物”這一古老的分類方式至今仍在大眾詞彙中有所反映。暖血動物包括哺乳動物和鳥類,其它動物統統被視為冷血動物。但是對更多物種進行的研究表明這種分類顯然是不適當的。美洲一種小型蜥蜴和沙漠鬣蜥同屬冷血動物,但實際上它們的體溫通常只比人類的體溫低1~2度,因此並不是真正的冷血。因此又出現了恆溫動物(即保持恆定體溫的動物)和變溫動物(即體溫隨外界環境的變化而改變的動物)這一區分方式。但這種分類也不恰當。因為有不少哺乳動物在冬眠期間會改變體溫,而許多生活在深海的無脊椎動物在寒冷的深海水域中體溫並不變化,而是恆定的。

Xìbāo yǔ wēndù

Xìbāo zhǐ néng zài yīdìng de wēndù fànwéi nèicún huó, ér jìnyībù bǎozhèng tāmen yǒuxiào gōngzuò de wēndù fànwéi jiù gèng xiǎole. Bǔrǔ dòngwù hé niǎo lèi de méi xìtǒng zhǐ néng zài 37℃zuǒyòu de hěn xiǎo fànwéi nèi cáinéng yǒuxiào gōngzuò. Yǔ cǐ xiāngchà jǐn jǐ dù de wēndù dūhuì dàdà xuēruò tāmen de gōngzuò xiàolǜ. Jǐnguǎn wēndù biànhuà gèng dà shí xìbāo réng néng cúnhuó, dàn jītǐ xìtǒng de zhěngtǐ yùnxíng nénglì què bèi xuēruòle. Qítā dòngwù duì tǐwēn de biànhuà yǒu gèng qiáng de shìyìng xìng. Jǐ gè shìjì yǐlái, rénmen jiù rènshi dào bǔrǔ dòngwù hé niǎo lèi tiáojié tǐwēn de fāngshì yǔ qítā dòngwù bùtóng. Suízhe shíjiān de tuīyí, rénmen duì zhè zhǒng chāyì de miáoshù yuè lái yuè jīngquè hé yǒu yìyì, dànshì”nuǎn xuè dòngwù” hé”lěngxuè dòngwù”zhè yī gǔlǎo de fēnlèi fāngshì zhìjīn réng zài dàzhòng cíhuì zhōng yǒu suǒ fǎnyìng. Nuǎn xuè dòngwù bāokuò bǔrǔ dòngwù hé niǎo lèi, qítā dòngwù tǒngtǒng bèi shì wéi lěngxuè dòngwù. Dànshì duì gèng duō wùzhǒng jìnxíng de yánjiū biǎomíng zhè zhǒng fēnlèi xiǎnrán shì bù shìdàng de. Měizhōu yì zhǒng xiǎoxíng xīyì hé shāmò liè xī tóngshǔ lěngxuè dòngwù, dàn shíjì shang tāmen de tǐwēn tōngcháng zhǐ bǐ rénlèi de tǐwēn dī 1~2 dù, yīncǐ bìng bùshì zhēnzhèng de lěngxuè. Yīncǐ yòu chūxiànle héngwēn dòngwù (jí bǎochí héngdìng tǐwēn de dòngwù) hé biànwēn dòngwù (jí tǐwēn suí wàijiè huánjìng de biànhuà ér gǎibiàn de dòngwù) zhè yī qūfēn fāngshì. Dàn zhè zhǒng fēnlèi yě bù qiàdàng. Yīnwèi yǒu bù shǎo bǔrǔ dòngwù zài dōngmián qíjiān huì gǎibiàn tǐwēn, ér xǔduō shēnghuó zài shēnhǎi de wú jǐchuí dòngwù zài hánlěng de shēnhǎi shuǐyù zhōng tǐwēn bìng bù biànhuà, ér shì héngdìng de.