跟读练习: How does the morning-after pill prevent pregnancy? - Alison Edelman - 通过YouTube学习英语口语
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In a 2021 study, researchers asked over 500 participants a simple question:
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In a 2021 study, researchers asked over 500 participants a simple question:
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how does the morning-after pill work?
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Despite these pills widespread use, 60% answered incorrectly.
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Emergency contraceptives are often misunderstood.
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In fact, even the phrase “the morning-after pill” is a misnomer.
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So, how do they work?
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Each month, the brain and the ovaries prepare an egg to be released.
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First, a group of immature eggs start to grow protective, fluid-filled sacs called follicles.
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Around the eighth day, one of these follicles becomes mature or dominant, and the others are reabsorbed.
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At this point, the brain signals the pituitary gland to produce luteinizing hormone, often just called LH.
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A big surge in LH tells the dominant follicle to rupture, releasing the egg.
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This is ovulation.
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The egg travels to the fallopian tube, where it stays for about 24 hours, and it’s only in this very short window that it can be fertilized by sperm.
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The rise of LH also stimulates the production of a hormone called progesterone.
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When progesterone binds at specific receptors, this also helps to signal ovulation.
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And high levels of progesterone are vital for preparing the uterine lining to support the possible implantation of a fertilized egg.
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So, where do emergency contraceptive pills come into play?
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Emergency contraceptives are not abortion pills.
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Instead, they work much earlier in the process before pregnancy, by disrupting or delaying ovulation.
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There are two main types of pills.
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The first type, sometimes called Plan B, contains a molecule called levonorgestrel, which is structurally very similar to the body’s hormone, progesterone.
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When taken, levonorgestrel interferes with the production of LH.
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Because LH doesn’t surge, there’s no ovulation.
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That said, Plan B needs to be taken before an LH surge.
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It can’t prevent ovulation once LH starts rising.
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The second type of pill contains a molecule called ulipristal acetate.
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It works by blocking progesterone from binding at receptors, thereby delaying ovulation.
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Ulipristal acetate works even if LH has already begun to rise, which means it’s effective in a wider window of time than Plan B.
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Since both pills work by blocking or delaying ovulation, the name “the morning-after pill” can be misleading.
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Emergency contraceptives are most effective when taken as soon as possible after sex, to better the chance of disrupting ovulation before it occurs.
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There is no need to wait until morning.
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For this reason, many healthcare providers suggest having them on hand.
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Yet emergency contraceptives may still prevent pregnancy even if they’re taken 3 to 5 days after sex, depending on the pill.
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That’s because sperm can live in the reproductive tract for about five days.
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So, for example, if a person ovulates three days after having unprotected sex, there's still a chance of pregnancy.
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Since it's difficult to know exactly where someone is in their cycle, it’s best to take emergency contraceptives as soon as possible.
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But perhaps the most widely held misconception about these pills is that they can harm a person’s future fertility.
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Decades of research have shown that this isn’t the case, even if emergency contraceptives are taken multiple times.
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In fact, the effects of both pills are short lived, and they don't provide continued protection.
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It's recommended that a person uses condoms for the remainder of their cycle, and if they have unprotected sex again, then repeat use.
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Of course, emergency contraceptive pills aren’t failproof.
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As they neither prevent fertilization nor the implantation of a fertilized egg, these pills are ineffective if someone has already ovulated, or the LH surge has already peaked.
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However, there is a third option that can protect against pregnancy, even if a person has already ovulated.
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Many people know copper intrauterine devices, or IUDs, as a form of long-term birth control, but they also work to prevent pregnancy if inserted soon after unprotected sex.
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Unlike emergency contraceptive pills, a copper IUD can prevent pregnancy before and after fertilization.
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Copper is toxic to sperm and creates a uterine environment that makes implantation unlikely.
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Of course, copper IUDs might be less accessible in an emergency situation— they must be inserted by a trained healthcare provider.
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But on the upside, they continue to prevent pregnancy for at least 10 years while in place.
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Most healthcare providers agree that it's more effective, as well as less expensive, to use a regular form of birth control when trying to avoid pregnancy.
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But if or when you need it, emergency contraceptives are a safe option to use.
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关于本课
这段视频深入浅出地解释了紧急避孕药（俗称“事后避孕药”）如何预防怀孕，并纠正了许多常见误解。通过学习本视频，您将不仅掌握相关生理学知识，还能极大地提升您的英语口语练习能力，尤其是用英语清晰地解释科学概念和纠正误解的能力。您将练习：
- 词汇主题： 掌握生殖生理学中的关键术语，如排卵（ovulation）、卵泡（follicle）、黄体生成素（luteinizing hormone, LH）、孕酮（progesterone）、受精（fertilization）和着床（implantation）等。
- 语法模式： 练习使用因果关系句式、对比句式以及解释复杂流程的句式，这对于提升您的英语流利度至关重要。
- 口语场景： 学习如何自信、准确地阐述科学信息，并纠正听众的错误观念，这对雅思口语等考试中讨论复杂话题非常有益。
重要词汇和短语
- misnomer: （误称，名称不当） 指一个名称不准确或具有误导性，例如“the morning-after pill”就是一种误称。
- disrupting or delaying ovulation: （干扰或延迟排卵） 这是紧急避孕药发挥作用的核心机制。
- structurally very similar to: （结构上与...非常相似） 用于描述化学分子或物质在结构上的相似性，对理解药物作用原理很有帮助。
- binds at specific receptors: （结合到特定受体上） 生物学中描述激素或药物如何与细胞相互作用的关键短语。
- short-lived effects: （短暂的效果） 形容某种作用或影响持续时间不长。
- failproof: （万无一失的） 并非绝对有效或没有失败风险。视频中指出紧急避孕药并非万无一失。
- on hand: （随时备有，手头有） 指某物随时可用，触手可及。
- toxic to sperm: （对精子有毒性） 描述某些物质对精子有害的作用，如铜制宫内节育器。
本视频练习技巧
本视频的主讲人语速适中，发音清晰，是进行跟读技巧训练的绝佳素材。
- 语速： 建议您在初次跟读时，先以稍慢于视频的速度练习，确保每个词都发音到位。熟练后，再尝试逐步跟上原始语速，这将显著提升您的英语流利度。注意她停顿和强调的地方，模仿其语调变化。
- 口音与发音： 讲者是标准的北美口音，吐字清晰。在进行发音练习时，特别关注视频中出现的医学专有名词，例如 "levonorgestrel"、"ulipristal acetate" 和 "luteinizing hormone"。这些词多音节、发音复杂，是挑战您发音准确性的好机会。尝试多次重复，直到能流利、准确地读出。
- 话题难度： 视频内容涉及生物学和医学知识，词汇专业性较强。在跟读时，除了模仿发音，还要尝试理解句子的结构和逻辑，例如如何清晰地解释“because LH doesn’t surge, there’s no ovulation”这样的因果关系。这将帮助您在雅思口语等高级英语交流中，更好地处理复杂和抽象的话题。
- 具体跟读建议： 尝试逐句模仿讲者的语气和连读，例如她如何自然地将“often misunderstood”和“structurally very similar”连读。注意她解释概念时的自信和权威感，这有助于您在未来的英语表达中展现专业性。
什么是跟读法？
跟读法 (Shadowing) 是一种有科学依据的语言学习技巧，最初开发用于专业口译员的培训，并由多语言者Alexander Arguelles博士普及。这个方法简单而强大：您在听英语母语原声的同时立即大声重复——就像是一个延迟1-2秒紧跟说话者的影子。与被动听力或语法练习不同，跟读法强迫您的大脑和口腔肌肉同时处理并模仿真实的讲话模式。研究表明它能显着提高发音准确性，语调，节奏，连读，听力理解和口语流利度——使其成为雅思口语备考和真实英语交流最有效的方法之一。