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    《ISPN学习》总第506期
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    《ISPN学习》总第720期
    日期:2020-12-21 19:35:00    
     
    《ISPN学习》2020年12月21日总第720期
     

    Vocabulary
     
    accomplish – n. 实现,达到
    fine-tuning – n. 微调,细调
    negative feedback – 负反馈
    hypothalamic–pituitary axis (HPA) -- 下丘脑-垂体轴
    law – n. 定律,规则
    sense – v. 感知,感觉
    secrete – v. 分泌
    release – v. 释放
    factor – n. 因子
    backup – a. n. 备用(的),辅助(的)
    override – v. 不顾,超越,不理
    exogenous – a. 外源的,外生的
    target organ – 靶器官,目标器官
    somatostatin – n. 生长抑素
    feedback loops – 反馈环

     
    ISPN Review
     
    Endocrine Regulation 内分泌调节                
     
    The production and release of hormones needs to be tightly regulated within the body. Hormones are released in small amounts to accomplish what needs to be done to maintain homeostasis within the body. The fine-tuning and regulation of hormone release through the hypothalamus are often regulated by a series of negative feedback systems. Other hormones are not controlled in this fashion but respond to other direct stimuli.

    激素的生产和释放需要身体内部的紧密调节。激素释放量小,完成所需任务,维持身体内部环境的稳定。下丘脑的激素释放的微调和调节经常由一系列的负反馈系统控制。其他激素不采取这种控制方式,而是通过响应其他直接刺激做出调节。

    Hypothalamic–Pituitary Axis 下丘脑-垂体轴

    Because of its position in the brain the hypothalamus is stimulated by many things, such as light, emotion, cerebral cortex activity, and a variety of chemical and hormonal stimuli. Together, the hypothalamus and the pituitary function closely to maintain endocrine activity along what is called the hypothalamic–pituitary axis (HPA) using a series of negative feedback systems.

    由于其在大脑所处位置,下丘脑受到很多因素刺激,如光、情感、大脑皮质活动及各种化学和激素刺激。下丘脑和垂体密切协同,沿着所谓的下丘脑-垂体轴(HPA),利用系列负反馈系统,维持内分泌活动。

    A negative feedback system works much like the law of supply and demand in business. In business, when there is an adequate supply of a product, production of that product will slow down because there is an adequate supply and no current demand for it. When the supply is used up, demand will increase, and so production will pick up. Production continues until the supply is adequate and demand is reduced. When the hypothalamus senses a need for a particular hormone—for example, thyroid hormone—it secretes the releasing factor TRH directly into the anterior pituitary. In response to the TRH the anterior pituitary secretes TSH, which in turn stimulates the thyroid gland to produce thyroid hormone. When the hypothalamus senses the rising levels of thyroid hormone, it stops secreting TRH, resulting in decreased TSH production and subsequent reduced thyroid hormone levels. The hypothalamus, sensing the falling thyroid hormone levels, secretes TRH again. The negative feedback system continues in this fashion, maintaining the levels of thyroid hormone within a relatively narrow range of normal.

    负反馈系统的工作原理很象商业中的供求规则。在商业活动中,当某种产品供应充足时,产品的生产就会减缓,因为供应充足,当前没有需求。当供应用完时,需求增加,产品生产加快,生产继续,直到供应充足需求下降。当下丘脑感知某特定激素需要时,如甲状腺激素,它就超乎分泌释放因子TRH进入垂体前叶。垂体前叶响应TRH,分泌TSH,此举转而刺激甲状腺产生甲状腺激素。当下丘脑感知甲状腺激素水平升高时,它就停止分泌TRH,导致TSH产量下降,并因此导致甲状腺激素水平降低。下丘脑感知甲状腺激素水平下降,再次分泌TRH。负反馈系统就以这种方式周而复始,将甲状腺激素水平维持在一个相对狭窄的正常范围内。

    It is thought that this feedback system is more complex than once believed. The hypothalamus probably also senses TRH and TSH levels and regulates TRH secretion within a narrow range, even if thyroid hormone is not produced. The anterior pituitary may also be sensitive to TSH levels and thyroid hormone, regulating its own production of TSH. This complex system provides backup controls and regulation if any part of the HPA fails. This system also can create complications, especially when there is a need to override or interact with the total system, as is the case with hormone replacement therapy or the treatment of endocrine disorders. Supplying an exogenous hormone, for example, may increase the hormone levels in the body, but then may affect the HPA to stop production of releasing and stimulating hormones, leading to a decrease in the body’s normal production of the hormone.

    人们认为,该反馈系统比曾经相信的更为复杂。下丘脑可能也感知TRH和TSH水平,在一个狭窄范围内调节TRH分泌,即使在甲状腺激素未生产的情况下。垂体前叶也可能对TSH水平和甲状腺激素敏感,调节本身的TSH产量。一旦HPA功能障碍,该复杂系统就可以提供辅助控制和调节。该系统还会造成并发症,特别是当需要超越或与总系统相互作用时,如在激素替代疗法或内分泌疾病治疗时。例如,提供外源激素可以增加身体激素水平,但也会影响PHA停止释放和刺激激素的生产,导致身体正常激素生产的减少。

    Two of the anterior pituitary hormones (i.e., GH and PRL) do not have a target organ to produce hormones and so cannot be regulated by the same type of feedback mechanism. The hypothalamus in this case responds directly to rising levels of GH and PRL. When levels rise the hypothalamus releases the inhibiting factors somatostatin and PIF directly to inhibit the pituitary’s release of GH and PRL, respectively. The HPA functions through negative feedback loops or the direct use of inhibiting factors to constantly keep these hormones regulated.

    两种垂体前叶激素(即GH和PRL)没有生产激素的目标器官,因此,不受同类型反馈机制的调节。在这种情况下,下丘脑直接作出反应,提升GH和PRL水平。当水平升高时,下丘脑释放抑制因子生长抑素和PIF直接分别抑制垂体释放GH和PRL。HPA通过负反馈环或直接利用抑制因子,不断调节这些激素。

     
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    Video  
     
    Hypothalamus
     
     
    Test  
     
    1. Which statement about the hypothalamus is correct?
    A. The hypothalamus is connected to the brain by the infundibulum
    B. The hypothalamus is composed of glandular epithelial tissue
    C. The hypothalamus secretes “releasing hormones”
    D. The hypothalamus secretes epinephrine and norepinephrine
    2. Which structure controls the endocrine system and integrates the activities of the nervous and endocrine systems?
    A. The infundibulum
    B. The pituitary gland
    C. The thalamus
    D. The hypothalamus
    .
     
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    答案 Answers
    1. C: The hypothalamus secrets “releasing hormones”
    Rationale: The hypothalamus is part of the brain so is composed of neural tissue. Epinephrine and norepinephrine are released from the adrenal medulla.
    2. D. The hypothalamus
    Rationale: Hypothalamus secretes regulatory hormones that control endocrine cells in the antepituitary gland; produces ADH and oxytocin; contains “autonomic centres” that exert neural control over endocrine cells of the adrenal medullae.

     
     

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