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  • 指甲和头发

    A close-up of a hairy arm with drops of water on it.

    Why do you have arm hair?
    ::为什么你有胳膊毛?

    Hair covers much of our bodies. But why? Think of the way that you can sense something brush against your arm. Your arm hair is important in providing this type of sensation and making you aware of your environment. Also, hair can trap heat and keep your body warm.
    ::头发覆盖了我们大部分的身体。 但是为什么? 想想你能感觉到什么东西在你的手臂上刷刷。 你的头发在提供这种感觉和让你了解环境方面很重要。 还有, 头发可以捕捉热和保持身体的温暖。

    Hair and Nails
    ::头发和指甲

    Along with the skin, the integumentary system includes the nails and hair. Both the nails and hair contain the tough , keratin . The keratin forms fibers, which makes your nails and hair tough and strong. Keratin is similar in toughness to chitin , the found in the exoskeleton of .
    ::与皮肤一起,内脏系统包括指甲和毛发。指甲和头发都包含坚硬的Keratin纤维,使你的指甲和头发坚固和坚固。Keratin与在外骨骼发现的Chitin相似。

    Nails
    ::针甲

    Nails are similar to claws in other . They cover the tips of fingers and toes. Fingernails and toenails both grow from nail beds. As the nail grows, more are added at the nail bed. Older cells get pushed away from the nail bed and the nail grows longer. There are no nerve endings in the nail. Otherwise cutting your nails would hurt a lot!
    ::指甲和脚趾都从指甲床长出来。 随着指甲的长长,指甲床会增加更多。 年长的牢房被从指甲床推开,钉子会长得更长。 指甲没有神经末端。 否则剪指甲会伤害很多!

    Nails act as protective plates over the fingertips and toes. Fingernails also help in sensing the environment. The area under your nail has many nerve endings. These nerve endings allow you to receive more information about objects you touch.
    ::指甲作为指尖和脚趾的防护板。 指甲也有助于感知环境。 您指甲下的区域有许多神经末端。 这些神经末端允许您获得更多关于您触碰的物体的信息 。

    The Guinness Book of World Records began tracking record fingernail lengths in 1955. At that time the record was 1 foot 10.75 inches long. The current record-holder for men is from India, with a record of 20 feet 2.25 inches for all nails on his left hand, the longest being his thumbnail at 4 feet 9.6 inches. The record for women is held by an American woman. The record is 28 feet (850 cm) for all nails of both hands, with the longest nail on her right thumb at 2 feet 11 inches. Since adult nails grow at about 3 mm a month (1/10 of an inch), how long would it take to grow such long nails?
    ::1955年,《世界记录吉尼斯书》开始追踪创记录的指甲长度。当时的记录是1英尺10.75英寸长。目前男性的记录持有者来自印度,左手所有钉子的记录为20英尺2.25英寸,左手所有钉子的记录为20英尺2.25英寸,最长的记录为4英尺9.6英寸的拇指,女性的记录为美国女性的记录。双手所有钉子的记录为28英尺(850厘米),右拇指上最长的指甲为2英尺11英寸。自成人指甲每月增长约3毫米(每英寸1/10英寸)以来,长这么长的指甲需要多长时间?

    Hair
    ::毛发

    Hair is one of the defining characteristics of mammals . In fact, mammals are the only animals to have hair. Hair sticks out from the epidermis , but it grows from the dermis ( Figure ). Hair grows from inside the hair follicle . New cells grow in the bottom part of the hair, called the bulb. Older cells get pushed up, and the hair grows longer. The cells that make up the hair strand are dead and filled with the rope-like protein keratin.
    ::毛发是哺乳动物的特征之一。 事实上, 哺乳动物是唯一有头发的动物。 毛发从毛皮上长出来, 但它从皮质上长出来 。 毛发从毛发囊中长出来 。 新的细胞在毛发底部生长, 叫做灯泡 。 更年长的细胞被拉起来, 头发长长。 构成毛发的细胞已经死亡, 并充满了像绳子一样的蛋白质板。

    Hair structure, follicle, and associated oil gland in the skin.

    Hair, hair follicle, and oil glands. The oil, called sebum, helps to prevent water loss from the skin. The sebaceous gland secretes sebum, which waterproofs the skin and hair.
    ::毛发、毛发泡和油腺。 油油叫做沙本,有助于防止皮肤水流失。 沙本的沙本分泌了防水的沙本,它保护了皮肤和头发。

    In humans, hair grows everywhere on the body except the soles of the feet and the palms of the hands, the lips, and the eyelids (except for eyelashes). Hair grows at a rate of about half an inch (1.25 cm) each month, or about 6 inches (15 cm) a year.
    ::在人类身上,除了脚底和手掌、嘴唇和眼皮(除睫毛外)之外,全身的毛发到处增长。 头发每月大约生长半英寸(1.25厘米),每年大约生长6英寸(15厘米)。

    Hair, especially on the head, helps to keep the body warm. The air traps a layer of warm air near the skin and acts like a warm blanket. Hair can also act as a filter. Nose hair helps to trap particles in the air that may otherwise travel to the lungs . Eyelashes shield from dust and sunlight. Eyebrows stop salty sweat and rain from flowing into the eye.
    ::毛发,特别是头部的毛毛,有助于保持身体的温暖,空气将一层温暖的空气困在皮肤附近,就像一个温暖的毯子一样。毛发也可以起到过滤器的作用。鼻毛有助于将可能进入肺部的微粒困在空气中。眼膜挡住灰尘和阳光。眼眉可以阻止盐状的汗水和雨水流进眼睛。

    The world's longest documented hair, according to Guinness World Records, belongs to Xie Qiuping of China at just under 18 feet 6 inches (5.627 m) when measured on May 8, 2004. She had been growing her hair since 1973 when she was 13 years old.
    ::根尼斯世界纪录显示,世界上记录时间最长的毛发属于中国谢珠,在2004年5月8日测量的18英尺以下6英寸(5.627米)处属于中国。 2004年5月8日,她从1973年13岁开始长发。

    Summary
    ::摘要

    • Hair and nails are made of keratin, a tough protein.
      ::头发和钉子都是用氯丁烷做的 坚硬的蛋白质
    • Nails act as protective plates over the fingertips and toes.
      ::指甲在指尖和脚趾上充当保护板。
    • Hair serves many functions such as acting as a filter and keeping the body warm.
      ::毛发发挥许多功能,例如充当过滤器和保持身体温暖。

    Explore More
    ::探索更多

    Use the resources below to answer the questions that follow.
    ::利用以下资源回答以下问题。

    • Skin, Hair, Nails at (1:12)
      ::皮肤、毛发、指甲(1:12)
    1. What is the function of your nails?
      ::你的指甲有什么作用?
    2. What is the function of the oil glands in your skin?
      ::你皮肤上油腺的功能是什么?
    3. What are the functions of hair?
      ::头发的功能是什么?

    Review
    ::回顾

    1. What is keratin?
      ::什么是柯拉廷?
    2. What are two functions of your nails?
      ::你的指甲有两个功能?
    3. What are two functions of your hair?
      ::你头发的两个功能是什么?
    4. What animals, other than mammals, have hair?
      ::除了哺乳动物,还有别的动物有头发吗?