31 Skin: It Has You Covered-Mid

Skin It Has You Covered FOCUS Question What are the functions of your skin?

你的皮肤有什么功能?

Your Amazing Skin! Skin Your body is covered in it. But what is skin, and why do you need it? Skin is the body's largest organ. An organ is a part of the body that has a specific and important function, such as your heart or lungs. Skin is a part of the excretory system, the system that rids the body of waste. But it does much more than that. Skin covers and protects your muscles, bones, blood vessels, and other parts of the body It protects your body. from the outside world. It keeps most fluids inside the body and germs out. It's a waterproof coat, and it keeps the body from getting too hot or too cold. Skin also allows us to sense the outside world. Math Moment Skin makes up about 15 of a person's body weight. If a person weighs 160 pounds. about how much does their skin weigh? (Hint: Multiply by 0.15 to solve the problem.)

你神奇的皮肤!皮肤你的身体被它覆盖着。 但是皮肤是什么，为什么你需要它? 皮肤是人体最大的器官。 器官是身体具有特定和重要功能的一部分，例如你的心脏或肺。 皮肤是排泄系统的一部分，排泄系统清除身体废物。 但它的作用远不止这些。 皮肤覆盖并保护你的肌肉、骨骼、血管和身体的其他部位。 从外面的世界。它能把大部分液体留在体内，把细菌挡在外面。 这是一件防水外套，它可以防止身体太热或太冷。 皮肤还能让我们感知外部世界。 皮肤约占一个人体重的15%。 如果一个人重160磅。 他们的皮肤有多重? (提示:乘以0.15就能解决问题。)

On the Surface Skin covers your whole body, but it is thicker in some places and thinner in others. The area around your eyes and eyelids has the thinnest skin. The bottom of your feet and palms of your hands have the thickest skin. All skin is divided into three layers: the epidermis the dermis, and the hypodermis. The epidermis is the thin outer layer. It is composed of dead, flattened cells at the surface of the body Epidermis cells are constantly dying, flaking off, and being replaced by cells from below. Washing your skin helps remove the dead cells. We replace our epidermis about every thirty-five days.

在表层皮肤覆盖你的整个身体，但它在某些地方较厚，在其他地方较薄。 眼睛和眼睑周围的皮肤最薄。 脚底和手掌的皮肤最厚。 所有的皮肤都分为三层:表皮、真皮层和皮下皮层。 表皮是薄薄的外层。 表皮细胞不断地死亡，剥落，并被下面的细胞所取代。 清洗皮肤有助于去除死细胞。 我们的表皮大约每35天更换一次。

Did you know that your nails and hair are part of your skin? Like all skin, they contain keratin, a type of protein produced in the epidermis. Keratin gives your body a strong, flexible covering. It helps make skin waterproof and keeps out germs and chemicals from the environment. The epidermis also produces a substance called melanin. Melanin protects skin from the harmful ultraviolet rays of the Sun. It also gives skin color. People born with darker skin produce more melanin than people with lighter skin When exposed to sunlight, your skin. produces more melanin and becomes a darker color. Do You Know? Freckles are small groups of cells that contain more melanin. People with lighter skin are more likely to form freckles.

你知道指甲和头发是皮肤的一部分吗? 像所有的皮肤一样，它们含有角蛋白，这是一种在表皮层产生的蛋白质。 角蛋白为你的身体提供了一层坚固、灵活的保护层。 它有助于皮肤防水，防止细菌和化学物质进入环境。 表皮也会产生一种叫做黑色素的物质。 黑色素保护皮肤免受太阳有害紫外线的伤害。 它还赋予皮肤颜色。天生肤色较深的人会比肤色较浅的人产生更多的黑色素。 产生更多的黑色素，颜色变深。 你知道吗?雀斑是含有更多黑色素的小细胞群。 肤色较浅的人更容易长雀斑。

Below the Surface The dermis is the middle layer of your skin (see diagram on page 3). It contains collagen, a type of tissue that connects the body together. Collagen makes skin firm but allows it to stretch and return to its shape like a rubber band. Tiny holes in the dermis, called pores, extend up into the epidermis. Some pores contain hair follicles—small tubes in the skin that hold each hair's root. Sebum is a kind of oil that moves up through the pores. Sebum keeps the skin moist, helps make it waterproof, and helps protect it from germs. Do You Know? Too much sebum can block pores with oil, dirt, and dead epidermis cells. and then become infected. The results are pimples Washing your skin to remove extra sebum can help keep pimples from forming.

真皮层是皮肤的中间层(见第3页的图表)。 它含有胶原蛋白，一种将身体连接在一起的组织。 胶原蛋白使皮肤紧致，但也能使皮肤像橡皮筋一样拉伸并恢复原状。 真皮层上的小孔叫做毛孔，向上延伸到表皮。 一些毛孔中含有毛囊——皮肤上的小管，包住每根发根。 皮脂是一种通过毛孔向上移动的油。 皮脂能保持皮肤湿润，防水，防止细菌侵袭。 你知道吗?过多的皮脂会堵塞毛孔中的油脂、污垢和死亡的表皮细胞。 然后被感染清洗皮肤去除多余的皮脂有助于防止痘痘的形成。

Blood vessels in the dermis provide nutrients to the skin. These blood vessels, along with sweat glands, help control your body's temperature. When your body is too warm, the blood vessels expand to release heat at your body's surface. The sweat glands release water through pores. Water evaporating from your skin's surface cools the body. The dermis also has receptors and nerve endings that sense pressure, touch, pain, and temperature. The hypodermis (see diagram on page 3) is the deepest layer of skin. It attaches the dermis to muscles and bones. The hypodermis stores fat for quick energy. Fat also provides padding and insulates the body from temperature changes.

真皮层的血管为皮肤提供营养。 这些血管和汗腺一起帮助控制你的体温。 当你的身体太热时，血管就会扩张，在体表释放热量。 汗腺通过毛孔释放水分。 皮肤表面蒸发的水分使身体降温。 真皮层也有感受器和神经末梢，可以感知压力、触觉、疼痛和温度。 皮下皮层(见第3页图表)是皮肤的最深层。 它将真皮层连接到肌肉和骨骼上。 皮下皮层储存脂肪以快速获得能量。 脂肪还能提供填充物，使身体免受温度变化的影响。