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  • Circadian Rhythms - 高级

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    What time do you get tired?
    ::你什么时候累?

    Everybody falls asleep. Your body needs to rest and recover from the day's activities. Usually you get tired around the same time every day. This happens because processes in your body occur in a 24-hour cycle.
    ::每个人都睡着。你的身体需要休息,从一天的活动中恢复过来。通常你每天在同样时间疲劳。这是因为你的身体过程是24小时循环的。

    Circadian Rhythms
    ::环环曲节奏

    is a behavior that usually occurs seasonally. Certain other behaviors, as well as many biological processes, have daily cycles. are regular changes in the biology and behavior of individuals that occur in 24-hour cycles. The term circadian comes from Latin words that mean “around a day.” Circadian rhythms occur in virtually all . In fact, they occur in most living organisms . In humans, all of the following biological characteristics or processes have roughly 24-hour cycles:
    ::一种通常季节性的行为。 某些其他行为, 以及许多生物过程, 都有日常周期。 它们是24小时周期中个人生物学和行为周期的定期变化。 circadian 这个词来自拉丁词,意思是“ 一天左右 ” 。 环球节奏几乎全部发生。 事实上, 它们发生在大多数活生物体中。 在人类中,以下所有生物特征或过程都有大约24小时周期:

    • Brain wave activity.
      ::脑波活动。
    • secretion.
      ::分泌
    • Urine production.
      ::尿液生产。
    • .
    • Body temperature.
      ::体温

    For example, the average adult human temperature changes in a regular way each day. It reaches its minimum in the middle of the night or very early in the morning. It reaches its maximum late in the afternoon.
    ::例如,成人平均气温每天以正常方式变化,在半夜或清晨达到最低温度,在下午达到最高温度。

    Circadian rhythms determine patterns of important behaviors in most animals, including feeding and sleeping patterns. In humans and other mammals , sleep patterns are partly controlled by a hormone called melatonin , which causes drowsiness. The hormone is secreted by the pineal gland , located in the brain. The secretion of melatonin changes predictably over a 24-hour cycle. The level of melatonin increases after darkness falls and drops to a very low level during daylight hours.
    ::环环曲节奏决定了大多数动物的重要行为模式,包括喂养和睡眠模式。在人类和其他哺乳动物中,睡眠模式部分受一种叫Melatonin的荷尔蒙控制,这导致沉睡。荷尔蒙由位于大脑中的松树腺秘而不宣。米拉托宁的分泌在24小时周期中可以预测会发生变化。在黑暗过后,梅拉托宁的水平会上升,白天会下降到非常低的水平。

    Animals have internal biological clocks that help maintain circadian rhythms. The primary biological clock in mammals is a tiny structure called the suprachiasmatic (SCN). The SCN is located in the hypothalamus near the base of the brain. As shown in  Figure , light enters the eye and strikes the retina (see The and The concepts). The optic nerve carries signals about light from the retina to the SCN. The SCN, in turn, sends out signals that help control biological characteristics and processes, including those listed above. For example, when little or no light enters the , the SCN signals the pineal gland to secrete more melatonin. When light enters the eyes, the SCN signals the pineal gland to secrete less melatonin.
    ::哺乳动物的主要生物钟是一个叫做超先令(SCN)的小结构。SCN位于大脑底部附近的低丘脑中。如图所示,光进入眼睛,撞击视网膜(见“概念”和“概念”)。光神经从视网膜向SCN传送光信号。SCN反过来发出信号,帮助控制生物特征和过程,包括上面列出的那些特征和过程。例如,当光进入大脑底部时,SCN信号是松鼠腺,以隐藏更多的梅拉托宁。当光进入眼睛时,SCN信号是松鼠腺,以较少地隐藏梅拉托宁。

    light controls many human biological processes
    This diagram shows how light controls many human biological processes and characteristics that have roughly 24-hour cycles, or circadian rhythms. Light enters the eye and strikes the retina, which sends signals via the optic nerve to the suprachiasmatic nucleus (SCN). In response, the SCN sends signals that cause changes in many biological processes. For example, signals sent to the pineal gland change the amount of melatonin that the gland secretes. Melatonin, in turn, helps control the sleep-wake cycle.

    Figure  shows what happens to melatonin levels when a person remains in darkness for 24 hours. Melatonin secretion continues to cycle, but the cycle lengthens. Without light, melatonin secretion and other circadian rhythms operate on a cycle that is closer to 25 hours. Normally, the 24-hour cycle of daylight and darkness regulates the innate rhythms. Each day, light resets the cycle so it is 24 hours long.
    ::图表显示一个人在黑暗中停留24小时时, 米拉托宁水平会发生怎样的变化。 梅拉托宁分泌会继续循环, 但周期长度会延长。 没有光, 米拉托宁分泌和其他环卡色节奏会在一个接近25小时的循环中运作。 通常, 24小时的日光和黑暗循环会调节内在的节奏。 每天, 灯光会重现循环, 所以它会持续24小时 。

    lesson content
    With normal daily changes in light, melatonin secretion has a 24-hour cycle (left side of curve). In the absence of light, the same cycle is almost 25-hours long (right side of curve).

    Did you ever fly from one time zone to another? If you did, then you may have experienced a disruption of your circadian rhythms called jet lag. For example, if you traveled to a time zone that was three hours earlier than the time zone to which you are accustomed, you may have become sleepy three hours earlier than your usual bedtime. It generally takes a few days to adjust to a time difference such as this.
    ::你曾经从一个时区飞到另一个时区吗?如果你飞到另一个时区,那么你可能已经经历了一个被称作时滞的环形节奏的中断。例如,如果你旅行到一个比你习惯的时区早三小时的时区,你可能已经睡了比通常的睡觉时间早三小时。通常需要几天时间来适应这样的时间差。

    Summary
    ::摘要

    • Many biological processes have daily cycles dictated by each organism's circadian rhythm.
      ::许多生物过程都有每个生物体的节奏所决定的日常周期。
    • Circadian rhythms determine patterns of important behaviors in most animals, including feeding and sleeping patterns.
      ::环曲节奏决定了大多数动物的重要行为模式,包括进食和睡眠模式。
    • Animals have internal biological clocks that help maintain circadian rhythms.
      ::动物有内脏生物钟 帮助维持环礁的节奏

    Review
    ::回顾

    1. What biological characteristics or processes of humans are regulated by a 24-hour cycle?
      ::24小时周期规范了人类的哪些生物特征或过程?
    2. How does the primary biological clock work in mammals?
      ::基本生物钟在哺乳动物中是如何工作的?
    3. If left in complete darkness, how long does a human's circadian rhythm usually last?
      ::如果在完全黑暗中离开, 人类的Circadian节奏通常持续多久?