乳房的科学：英语精读讲义

Breasts, they provide nourishment for our babies.

乳房能为我们的宝宝提供营养。

They are one of the few organs not fully developed at birth 語法

乳房是少数几个在出生时尚未完全发育的器官之一，

and of course they are a major obsession in Western culture.

当然，它们也是西方文化中人们痴迷的一大对象。

Yet there is so much about breasts that isn't discussed or is deemed taboo. 用詞

然而，关于乳房，还有太多内容无人讨论，或被视为禁忌。

Sorry, taboo.

抱歉，是禁忌。

So what does science say about breasts?

那么，科学是怎么解释乳房的呢？

Forget water into wine, 講解

先别管什么变水为酒，

what about blood into milk?

血液变成乳汁又是怎么回事？

Proteins, sugars and fat are pulled from a mother's blood supply to make milk

蛋白质、糖和脂肪会从母亲的血液中提取出来，用来制造乳汁，

and it is this action that has made mammals so successful. 語法

正是这个过程让哺乳动物如此成功。

Unlike birds or reptiles whose young are dependent on parents to bring them outside food such as insects, 講解

鸟类或爬行动物的幼崽要依赖父母从外面带回昆虫等食物，哺乳动物则不同，

mammals from the word mammary access their nutrition at a young age from the secretion of a mother's milk.

“哺乳动物”这个名称源于乳腺，它们的幼崽在年幼时通过母亲分泌的乳汁获取营养。

Breasts come in all shapes and sizes 短語搭配

乳房的形状和大小各不相同，

and though there is a positive correlation between breast size and weight, 用詞

虽然乳房大小与体重呈正相关，

genes also play a crucial role in the size of boobs. 短語搭配

但基因也在胸部大小上起着关键作用。

50% of the time one breast is larger than the other,

在50%的情况下，一侧乳房会比另一侧大，

most commonly the left boob known as breast asymmetry.

最常见的是左侧较大，这种情况叫作乳房不对称。

This asymmetry is normal

这种不对称很正常，

and though scientists aren't entirely clear why, 表達脈絡

虽然科学家还不完全清楚原因，

a possible contributor is the hormonal changes that happen during puberty. 表達脈絡

但青春期发生的激素变化可能是成因之一。

On top of this, 表達脈絡

此外，

the size of your breasts vary from week to week. 短語搭配

你的乳房大小每周都可能不同。

Yep, the production of estrogen and progesterone throughout the menstrual cycle changes the size of your breasts.

没错，整个月经周期中雌激素和孕酮的分泌会改变乳房的大小。

Both men and women have nipples and mammary glands

男性和女性都有乳头和乳腺，

but usually only women have them develop at puberty.

但通常只有女性的乳腺会在青春期发育。

This characteristic is uniquely human as other mammals breasts only enlarge during nursing. 用詞

这一特征是人类独有的，因为其他哺乳动物的乳房只会在哺乳期变大。

The ring of pigmented skin surrounding the nipple is called the areola

乳头周围那圈带有色素的皮肤叫作乳晕，

which is covered in little bumps called Montgomery's gland.

上面布满了称为蒙哥马利腺的小凸点。

While lactating, 語法

在哺乳期间，

the glands make oily secretions that keep the nipple lubricated 語法

这些腺体会产生油性分泌物，让乳头保持润滑，

and may also release compounds to make the nipple seem yummy for a baby. 語法

还可能释放某些化合物，让宝宝觉得乳头很“美味”。

The nipple isn't composed of a single orifice 短語搭配

乳头并非只有一个开口，

but has many tiny holes you cannot see with the naked eye. 短語搭配

而是有许多肉眼看不见的微小孔洞。

After having a baby,

生完宝宝后，

receptors in the nipple detect when the baby begins to suckle

当宝宝开始吸吮时，乳头中的感受器会察觉到，

sending messages to the mother's brain 語法

并向母亲的大脑发送信号，

causing a release of oxytocin and continued production of prolactin.

促使催产素释放，并让催乳素持续分泌。

Oxytocin causes the cells that line the mammary glands to contract

催产素会让构成乳腺内壁的细胞收缩，

and it's also known as the cuddle hormone 用詞

它也被称为“拥抱激素”，

as it enhances the bonding experience between mother and child.

因为它能增强母亲与孩子之间的亲密联结。

The hormone prolactin is essential in making milk.

催乳素是制造乳汁必不可少的激素。

This whole hormonal process can be triggered after only hearing a baby cry 用詞

整个激素过程甚至只要听到婴儿哭声就会被触发，

even if it isn't your baby. 語法

哪怕哭的并不是你的宝宝。

Babies love breasts but so do people. 語法

宝宝喜欢乳房，大人也一样。

Research has found that people spend more time observing large breasts with a certain hip to width ratio 講解

研究发现，如果一个人的臀部与身体宽度呈特定比例，人们会花更多时间注视其丰满的乳房，

potentially explaining why breast augmentation surgeries 表達脈絡

这或许能解释为什么隆胸手术

are the most prevalent form of plastic surgery

是最常见的整形手术，

with 300,000 surgeries being performed in 2014 in America alone. 語法

仅2014年，美国就进行了30万例。

However, the same research shows that people prefer breasts of all different shapes and sizes

不过，同一项研究显示，人们喜欢各种形状和大小的乳房，

and medium sized breasts were actually rated as statistically most attractive.

而从统计结果来看，中等大小的乳房其实最具吸引力。

Breasts don't only create joy for others 語法

乳房不只会给别人带来愉悦，

but also for oneself.

也会给自己带来愉悦。

Studies show that stimulation of nipples enhanced sexual arousal in 82% of women

研究显示，刺激乳头能增强82%女性的性兴奋，

and 52% of men.

男性中也有52%会如此。

Interestingly, an fMRI scan that mapped the brain's response to clitoral and vaginal self-stimulation

有趣的是，一项fMRI扫描绘制了大脑对阴蒂和阴道自我刺激的反应，

found that the same areas lit up when a woman stimulated her nipples. 短語動詞

结果发现，女性刺激乳头时，大脑中亮起的是相同区域。

Despite being an amazing source of both nutrition and pleasure, 語法

乳房既是绝佳的营养来源，也能带来愉悦，

breasts are incredibly vulnerable.

但它们也极其脆弱。

Breast cancer is the most prevalent form of cancer in North America.

乳腺癌是北美最常见的癌症。

Cells that divide often are at a higher risk of mutation than cells that don't divide 短語搭配

频繁分裂的细胞比不分裂的细胞更容易发生突变，

and because breasts change and grow over the course of our lives, 短語搭配

而乳房会在我们一生中不断变化和生长，

these cells are frequently dividing.

所以这些细胞经常分裂。

The hormone estrogen also stimulates breast cell division

雌激素也会刺激乳房细胞分裂，

and there are environmental chemicals found in pesticides, industrial products 語法

而农药和工业产品中存在一些环境化学物质，

and even our food that mimic estrogen 用詞

甚至我们的食物中也有，它们会模拟雌激素，

and can influence cell growth increasing the risk of breast cancer. 語法

并能影响细胞生长，从而增加患乳腺癌的风险。

Research is discovering new risk factors of breast cancer

研究正在发现乳腺癌的新风险因素，

such as breast density, age of first pregnancy

比如乳房密度、首次怀孕年龄，

and genetic predisposition to breast cancer genes such as BRCA1 and BRCA2. 用詞

以及与BRCA1和BRCA2等乳腺癌基因有关的遗传易感性。

This scientific knowledge can help increase prevention.

这些科学知识有助于加强预防。

Although they are vulnerable, they are incredible

乳房虽然脆弱，却也非同凡响，

and regardless of shapes and sizes, 短語搭配

无论形状和大小如何，

they are an essential aspect of sustaining human life

它们都是维系人类生命不可或缺的一部分，

and defining us as a species.

也帮助定义了我们这个物种。

Thank you boobs.

谢谢你们，乳房。

Want to learn even more about boobs?

想了解更多关于乳房的知识吗？

Check out our latest AsapThought video

快去看看我们最新的AsapThought视频，

where we debunk some myths about why women have breasts. 短語搭配

我们在其中驳斥了一些关于女性为何有乳房的错误说法。

Click on the screen or use the link in the description

点击屏幕，或使用简介中的链接，

and subscribe for more weekly science videos.

别忘了订阅，获取每周更新的更多科学视频。