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  • 内分泌激素

    Pills from Pee
    ::来自Pee的药丸

    The medication pictured above with the brand name Progynon was a drug used to control the effects of menopause in women. The pills first appeared in 1928 and contained the human sex hormone estrogen . Estrogen secretion declines in women around the time of menopause and may cause symptoms like  mood swings and hot flashes. The pills were supposed to ease the symptoms by supplementing estrogen in the body. The manufacturer of Progynon obtained estrogen for the pills from the urine of pregnant women, because it was a cheap source of the hormone. Progynon is still used today to treat menopausal symptoms. Although the drug has been improved over the years, it still contains estrogen, which is an example of an endocrine hormone.
    ::上面以品牌为Progynon的药物是用来控制女性更年期影响的药物,1928年首次出现,含有人类性激素雌激素; 更年期前后女性的雌激素分泌下降,可能导致情绪波动和热闪光等症状; 药丸本应通过补充体内雌激素来缓解症状; Progynon的制造商从孕妇尿中获取雌激素,因为它是荷尔蒙的一个廉价来源; Progynon今天仍然用于治疗更年期的症状; 尽管多年来该药物已有所改善,但仍含有雌激素,这是内分泌激素的一个例子。

    How Do Endocrine Hormones Work?
    ::内分泌激素如何工作?

    Endocrine hormones like estrogen are messenger molecules secreted by into the bloodstream. They travel throughout the body in the circulation. Although they reach virtually every in the body in this way, each hormone affects only certain cells, called target cells . A target cell is the type of cell on which a hormone has an effect. A target cell is affected by a particular hormone because it has receptor proteins  —  either on the cell surface or within the cell   — that are specific to that hormone. An endocrine hormone travels through the bloodstream until it finds a target cell with a matching receptor to which it can bind. When the hormone binds to the receptor, it causes changes within the cell. The manner in which it changes the cell depends on whether the hormone is a steroid hormone or a non-steroid hormone .
    ::雌激素等内分泌激素是分泌分子进入血液流的传递分子,在血液循环中贯穿整个身体,尽管它们以这种方式接触几乎所有身体,但每种荷尔蒙只影响某些细胞,称为目标细胞;目标细胞是荷尔蒙起作用的细胞类型;目标细胞受到某种荷尔蒙的影响,因为它在细胞表面或细胞内有该激素特有的受体蛋白;内分泌激素穿过血液流,直到发现一个目标细胞,有与之相匹配的受体;当荷尔蒙与受体结合时,它会在细胞内造成变化;它改变细胞的方式取决于该荷尔蒙是类激素,还是非类激素。

    Steroid Hormones
    ::类固醇激素

    A steroid hormone  (such as estrogen) is made of . It is fat soluble, so it can diffuse across a target cell’s plasma membrane, which is also made of lipids. Once inside the cell, a steroid hormone binds with receptor proteins in the cytoplasm . As you can see in the diagram , the steroid hormone and its receptor form a complex — called a steroid complex — which moves into the , where it influences the expression of genes . Examples of steroid hormones include cortisol, which is secreted by the adrenal glands , and sex hormones, which are secreted by the gonads .
    ::类固醇激素(如雌激素)是由类固醇(如雌激素)制成的。它是脂肪溶解的,因此可以扩散到目标细胞的血浆薄膜中,后者也是由脂质制成。一旦进入细胞,类固醇激素就会与细胞顶层的受体蛋白结合。正如你从图表中可以看到的那样,类固醇激素及其受体形成一个复合体 — — 被称为类固醇综合体 — — 进入该综合体,并影响基因的表达。类固醇的示例包括肾上腺和性激素所隐匿的皮质激素,后者被甲状腺腺和性激素所隐匿。

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    A steroid hormone crosses the plasma membrane of a target cell, binds with a receptor protein within the cytoplasm, and forms a complex that moves to the nucleus, where it affects gene expression.
    ::类固醇荷尔蒙穿过目标细胞的等离子膜,在细胞托盘中与受体蛋白结合,形成一个向核移动的复合体,影响基因表达。

    Non-Steroid Hormones
    ::非类固醇荷尔蒙

    A non-steroid hormone is made of amino acids . It is not fat soluble, so it cannot diffuse across the plasma membrane of a target cell. Instead, it binds to a receptor protein on the . In the following diagram, you can see that the binding of the hormone with the receptor activates an in the cell membrane. The enzyme then stimulates another molecule, called the second messenger , which influences processes inside the cell. Most endocrine hormones are non-steroid hormones. Examples include glucagon and insulin , both produced by the pancreas .
    ::非分子激素是由氨基酸制成的。它不是脂肪溶解性,因此不能在目标细胞的等离子膜中扩散。相反,它与受体蛋白绑在一起。在下图中,你可以看到荷尔蒙与受体的结合会激活细胞膜中的一种。酶然后刺激另一个分子,称为第二个送信者,它会影响细胞内的过程。大部分内分泌激素都是非分子激素。例子包括由胰腺生成的甘油和胰岛素。

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    A non-steroid hormone binds with a receptor protein on the plasma membrane of a target cell. This activates an enzyme, which controls a secondary messenger molecule.
    ::非小类荷尔蒙与目标细胞血浆膜上的受体蛋白结合。这激活了控制二级信使分子的酶。

    Regulation of Endocrine Hormones
    ::内分泌激素条例

    Endocrine hormones regulate many body processes, but what regulates the secretion of endocrine hormones? Most endocrine hormones are controlled by feedback mechanisms. A feedback mechanism is a loop in which a product feeds back to control its own production. Feedback loops may be either negative or positive.
    ::内分泌激素调节着许多体内过程,但什么调节了内分泌激素的分泌?大多数内分泌激素由反馈机制控制。反馈机制是产品回馈以控制自身生产的循环。反馈循环可以是负的,也可以是正的。

    • Most endocrine hormones are regulated by negative feedback loops. Negative feedback keeps the concentration of a hormone within a relatively narrow range, and maintains .
      ::大部分内分泌激素受负面反馈循环管制。 负面反馈将激素的浓度保持在相对狭窄的范围内,并维持住。
    • Very few endocrine hormones are regulated by positive feedback loops. Positive feedback causes the concentration of a hormone to become increasingly higher.
      ::很少有内分泌激素受到积极反馈循环的调节,积极反馈导致荷尔蒙的浓度越来越高。

    Regulation by Negative Feedback
    ::以否定反馈进行监管

    A negative feedback loop controls the synthesis and secretion of hormones by the thyroid gland . This loop includes the hypothalamus and pituitary gland , in addition to the thyroid, as shown in the diagram . When the levels of thyroid hormones circulating in the fall too low, the hypothalamus secretes thyrotropin releasing hormone (TRH). This hormone travels directly to the pituitary gland through the thin stalk connecting the two structures. In the pituitary gland, TRH stimulates the pituitary to secrete thyroid stimulating hormone (TSH). TSH, in turn, travels through the bloodstream to the thyroid gland, and stimulates it to secrete thyroid hormones. This continues until the blood levels of thyroid hormones are high enough. At that point, the thyroid hormones feed back to stop the hypothalamus from secreting TRH and the pituitary from secreting TSH. Without the stimulation of TSH, the thyroid gland stops secreting its hormones. Eventually, the levels of thyroid hormones in the blood start to fall too low again. When that happens, the hypothalamus releases TRH, and the loop repeats.
    ::负反馈循环控制甲状腺激素的合成和分泌。 这一循环包括甲状腺以外的下丘和下垂腺,如图所示。 当甲状腺激素水平在下降过低时,甲状腺激素会分泌出甲状腺激素(TRH) 。 这种激素会通过连接两个结构的细细小的跟踪直接进入垂状腺。 在下垂腺中,TRH会刺激垂垂垂体到隐性甲状腺刺激激素(TSH) 。 TSH会转而通过血液流到甲状腺腺,刺激其隐性激素。这一直持续到甲状腺激素的血液水平达到足够高的水平。 在这一点上,甲状腺激素会回味从秘密的TRHH和隐性TSH中阻止下垂体。 没有TSH的刺激, 甲状腺腺腺激素会停止分泌其激素。 最后, 血液中甲状腺激素的释放水平会再次下降。

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    This diagram shows how the thyroid gland is regulated by a negative feedback loop that also involves the hypothalamus and pituitary gland.
    ::该图显示甲状腺如何受到负面反馈循环的调节,该循环还涉及下丘和脑下腺。

    Regulation by Positive Feedback
    ::积极反馈条例

    Prolactin is a non-steroid endocrine hormone secreted by the pituitary gland. One of the functions of prolactin is to stimulate a nursing mother’s mammary glands to produce milk. The regulation of prolactin in the mother is controlled by a positive feedback loop that involves the nipples, hypothalamus, pituitary gland, and mammary glands. Positive feedback begins when a baby suckles on the mother’s nipple. from the nipple reach the hypothalamus, which stimulates the pituitary gland to secrete prolactin. Prolactin travels in the blood to the mammary glands and stimulates them to produce milk. The release of milk causes the baby to continue suckling, which causes more prolactin to be secreted and more milk to be produced. The positive feedback loop continues until the baby stops suckling at the breast.
    ::prolactin是一种非分子性内分泌激素,由垂死腺秘而不宣。 palactin的功能之一是刺激哺乳母亲哺乳腺生产牛奶。母亲对蛋白质的调节由积极的反馈循环控制,这种反馈循环涉及乳头、低脑、低脑腺和哺乳腺。当婴儿对母亲乳头的吸缩时,积极的反馈就会开始。从乳头到下脑,它会刺激垂死腺对蛋白进行分泌。蛋白质在血液中流向哺乳腺并刺激它们生产牛奶。 奶的释放导致婴儿继续吸奶,这导致更多的蛋白质被隐蔽并产生更多的牛奶。 积极的反馈循环会持续到婴儿停止在乳房吸奶为止。

    Feature: Myth vs. Reality
    ::特征:神话对现实

    Anabolic steroids are synthetic versions of the naturally occurring male sex hormone testosterone . Male hormones have androgenic (or masculinizing) effects, but they also have anabolic (or muscle-building) effects. The anabolic effects are the reason that synthetic steroids are used by athletes. In addition to building , they also accelerate the of and red blood cells , increase endurance so athletes can train harder and longer, and speed up muscle recovery. Unfortunately, these benefits of steroid use come with costs. If you ever consider taking anabolic steroids to build muscles and improve athletic performance, consider the following myths and corresponding realities.
    ::新陈代谢类固醇是自然形成的男性性激素睾酮的合成品,男性荷尔蒙具有诱变(或雄性化)效应,但也具有新陈代谢(或肌肉造形)效应。新陈代谢效应是运动员使用合成类固醇的原因。除建筑外,它们还加速红细胞和红细胞的生长,增加耐力,使运动员能够更长时间地训练,加速肌肉恢复。不幸的是,使用类固醇的这些好处也会带来代价。如果你考虑使用新陈代谢类固醇来制造肌肉,改善运动表现,那么考虑到以下的神话和相应的现实。

    Myth: Steroids are safe.
    ::传说:类固醇是安全的。

    Reality: Steroid use may cause several serious side effects. Prolonged use may increase the risk of liver , heart disease, and high .
    ::长期使用可能会增加肝脏、心脏病和高发风险。

    Myth: Steroids will not stunt your growth.
    ::传说:类固醇不会阻碍你的成长。

    Reality: Teens who take steroids before they have finished growing in height may have their growth stunted so they remain shorter throughout life than they would otherwise have been. Such stunting occurs because steroids increase the rate at which skeletal maturity is reached. Once skeletal maturity occurs, additional growth in height is impossible.
    ::真实性:在高度发育完成之前服用类固醇的青少年可能发育迟缓,因此在整个生命期保持比原来短的发育期。这种发育迟缓是因为类固醇提高了骨骼成熟率。一旦骨骼成熟,就不可能增加身高。

    Myth: Steroids do not cause drug dependency.
    ::传说:类固醇不引起药物依赖。

    Reality: Steroid use may cause dependency, as evidenced by the negative effects of stopping steroid use. These negative effects may include insomnia, fatigue, and depressed mood, among others.
    ::现实:类固醇的使用可能造成依赖性,停止类固醇使用的负面影响就是证明,这些负面影响可能包括失眠、疲劳和情绪低落等。

    Myth: There is no such thing as “roid rage.”
    ::传说:不存在“机器人狂怒”之类的东西。

    Reality: Steroid use has been shown to increase aggressiveness in some people. It has also been implicated in a number of violent acts committed by people who had not demonstrated violent tendencies until they started using steroids.
    ::实际情况:使用类固醇已经证明在一些人中增加了攻击性,它也与一些直到开始使用类固醇才表现出暴力倾向的人犯下的一些暴力行为有关。

    Myth: Only males use steroids.
    ::传说:只有男性使用类固醇。

    Reality: Although steroid use is more common in males than females, some females also use steroids. They use them to build muscle and improve physical performance, generally either for athletic or for self-defense.
    ::现实:尽管使用类固醇在男性中比女性更为常见,但一些女性也使用类固醇,他们利用类固醇培养肌肉,提高体能,一般是为了运动或自卫。

    Summary
    ::摘要

    • Endocrine hormones are messenger molecules secreted by endocrine glands into the bloodstream. They travel throughout the body but affect only certain cells, called target cells, which have receptors specific to particular hormones.
      ::内分泌激素是内分泌腺在血液中隐蔽的传递分子,它们在整个身体中流动,但只影响某些细胞,称为目标细胞,这些细胞有特定激素特有的受体。
    • Steroid hormones such as estrogen are endocrine hormones made of lipids that cross plasma membranes and bind to receptors inside target cells. The hormone-receptor complexes then move into the nucleus, where they influence gene expression.
      ::雌激素等类类固醇激素是由脂质组成的内分泌激素,这些脂质横跨等离子膜,并与目标细胞内的受体捆绑在一起。 荷尔蒙受体综合体随后进入核心,影响基因表达。
    • Non-steroid hormones (such as insulin) are endocrine hormones made of amino acids that bind to receptors on the surface of target cells. This activates an enzyme in the plasma membrane, and the enzyme controls a second messenger molecule, which influences cell processes.
      ::非小类激素(如胰岛素)是由氨基酸制成的内分泌激素,与目标细胞表面的受体捆绑在一起。这激活了血浆膜中的酶,酶控制了影响细胞过程的第二个信使分子。
    • Most endocrine hormones are controlled by negative feedback loops in which rising levels of a hormone feed back to stop its own production — and vice-versa. For example, a negative feedback loop controls production of thyroid hormones. The loop includes the hypothalamus, pituitary gland, and thyroid gland.
      ::大多数内分泌激素都受到负面反馈循环的控制,在这一循环中,荷尔蒙的回馈水平不断上升,以阻止自己的生产,反之亦然。例如,甲状腺激素的反反馈循环控制生产。 循环包括低脑、低脑腺和甲状腺。
    • Only a few endocrine hormones are controlled by positive feedback loops, in which rising levels of a hormone feed back to stimulate continued production of the hormone. Prolactin, the pituitary hormone that stimulates milk production by mammary glands, is controlled by a positive feedback loop. The loop includes the nipples, hypothalamus, pituitary gland, and mammary glands.
      ::只有少数内分泌激素受到积极反馈循环的控制,其中荷尔蒙的回馈水平不断上升,刺激荷尔蒙的持续生产。 活性激素,即刺激哺乳腺产奶的垂体性激素,受到积极反馈循环的控制。 循环包括乳头、下丘、垂体腺和哺乳腺。

    Review
    ::回顾

    1. What are endocrine hormones?
    ::1. 什么是内分泌激素?

    2. In the context of endocrine hormones, define target cells.
    ::2. 在内分泌激素方面,界定目标细胞。

    3. Explain how steroid hormones influence target cells.
    ::3. 解释类固醇激素如何影响目标细胞。

    4. How do non-steroid hormones affect target cells?
    ::4. 非小类荷尔蒙如何影响目标细胞?

    5. Compare and contrast negative and positive feedback loops.
    ::5. 比较和对比负面和正面反馈循环。

    6. Outline the way feedback controls the production of thyroid hormones.
    ::6. 概述反馈控制甲状腺激素生产的方式。

    7. Describe the feedback mechanism that controls milk production by the mammary glands.
    ::7. 说明控制哺乳腺牛奶生产的反馈机制。

    8. Why do endocrine hormones only affect some of the cells in the body? Choose the best answer.
    ::8. 为什么内分泌激素只影响身体的某些细胞?选择最好的答案。

    a. They only reach certain cells.
    ::a. 它们只达到某些细胞。

    b. Many hormones cannot cross the plasma membrane of cells.
    ::b. 许多荷尔蒙不能跨过细胞的等离子膜。

    c. Some cells feedback negatively in response to a hormone.
    ::c. 一些细胞对荷尔蒙反应反应不良。

    d. Only some cells have receptor proteins that can bind to a given hormone.
    ::d. 只有部分细胞有受体蛋白质,可与某种激素结合。

     

    9. People with a condition called hyperthyroidism produce too much thyroid hormone. What do you think this does to the level of TSH? Explain your answer.
    ::9. 患有超机器人病的人会产生过多甲状腺激素,认为这对TSH水平有何影响?解释你的答复。

     

    10. Which is more likely to maintain homeostasis — negative feedback or positive feedback? Explain your answer.
    ::10. 哪一种更有可能保持顺势——消极反馈或积极反馈?解释你的答复。

     

    11. Does testosterone bind to receptors on the plasma membrane of target cells or in the cytoplasm of target cells? Explain your answer.
    ::11. 睾酮是否与目标细胞等离子膜上的受体或目标细胞的细胞图层中的受体捆绑在一起?解释你的答复。

     

    12. True or False:  Endocrine hormones can affect the expression of genes.
    ::12. 真实或假:内分泌激素可能影响基因的表达。

     

    13. True or False:  Non-steroid hormones cannot affect intracellular processes.
    ::13. 真实或假:非小类荷尔蒙不能影响细胞内过程。

     

    14. True or False:  Insulin binds to receptors on the plasma membrane of cells.
    ::14. 真实或假:胰岛素与细胞等离子膜上的受体结合。

     

    15. Which hormone is secreted by the pituitary gland?
    ::15. 哪个荷尔蒙是脑垂体腺所隐蔽的?

    a. prolactin
    ::a. 丙烯酯

    b. insulin
    ::b. 胰岛素

    c. cortisol
    ::c. 焦分醇

    d. thyrotropin releasing hormone
    ::d. 胸激素释放激素

    Explore More
    ::探索更多

    For a funny and fast-paced lesson that covers endocrine hormones in greater detail, watch this CrashCourse video:
    ::更详细地报导内分泌激素, 观看这段CrashCourse视频:

    Check out this video to learn more about anabolic steroids:
    ::看看这段视频, 了解更多关于新陈代谢类固醇: