呼吸系统

The respiratory system of the human body is responsible for the distribution of the air inhaled and exhaled throughout a person's life. The respiratory system includes the nose, throat, voice box, wind pipe, and lungs.

人体的呼吸系统负责人一生吸入和呼出空气的气体交换。呼吸系统包括鼻、喉咙、喉头、气管和肺。

Each time a person inhales, or breathes in air, several kinds of gases enter the body. The most important is oxygen because it keeps a person alive, and the cells of the body need it for energy and growth. The air enters through the nose and mouth and the lungs fill up and then empty out. When the air is inhaled there are tiny hairs in the nose called cilia that filter the air. The air is also warmed and moistened as it travels through the nose. Cilia also protects other parts of the respiratory passages, filtering out dust and other particles.

每次人体吸入空气，会有几种气体的进入人体。最重要的是氧气，因为它是人的生存需要氧气，并且人体细胞需要氧气用于制造能量和生长。空气通过鼻子和嘴进入，填满肺部，然后排空。当空气被吸入时，鼻子内的纤毛过滤空气。鼻腔同样也温润了吸入的空气。而且鼻毛还过滤掉了吸入的灰尘和其他颗粒。

The inhaled air travels through the windpipe, which is called the trachea. The human body contains two lungs. The lungs are pink, mushy, and like a sponge. The lungs are protected by the rib cage and keeps them protected and safe. The lung on the left side of the body is smaller than the right lung, which allows room for a person's heart. Beneath the lungs is a muscle called the diaphragm. It works with the lungs to allow a person to inhale and exhale. When a person breathes in the diaphragm shrinks and levels out as the lungs fill up with air.

吸入的空气穿过气管。人体有两叶肺。肺是粉红色的糊状体，像海绵一样。肺部由肋笼保护。人体左侧的肺比右肺更小，因为左侧的心脏同样需要空间。肺的下部是膈肌。它与肺部协同工作使人体进行吸气和呼气。当一个人的吸气，膈肌收缩，肺部充满空气。

The end of the trachea is located between the two lungs. At the bottom of the trachea are a couple of large tubes called bronchi. The bronchi lead into the lungs. One tube sends air into the left lung, and the other tube sends air into the right lung.

气管的尾部在两肺之间。在气管的底部有几个大的管道成为支气管。支气管与肺部直接相连。一个支气管使空气进入左肺和另一支气管使空气进入右肺。

Once the air travels through the bronchi, it will branch off into smaller tubes called bronchioles. The bronchioles are about the thickness of a hair, and there are about 30,000 in each lung. From the bronchioles the air then continues its journey to tiny air sacs located throughout the lungs. The tiny air sacs are called alveoli.

空气进入支气管后，它将岔开成更小的细支气管。细支气管约为与头发粗细相当，每个肺约有30,000个细支气管。进入细支气管空气再继续穿过遍布肺部的微小气囊。而微小气囊被称为肺泡。

The 600 million alveoli are covered with very tiny blood vessels called capillaries. It is in this area of the lungs between the alveoli and capillaries the exchange of air takes place. Alveoli allow the air to pass into the blood cells of the body, first traveling through the heart carried by red blood cells. The oxygen enters the blood through the tiny capillaries. The heart then takes the blood filled with oxygen and sends it out to all the cells of the body.

6亿个肺泡上都覆盖着非常微小的血管称为毛细血管。肺泡与肺泡之间以及毛细血管之间发生的便是肺部的空气交换。肺泡让空气进入人体血细胞，首先就是通过红血细胞将空气运送到心脏。氧气通过毛细血管进入血液。然后心脏吸收充满氧气的血液并将其运输到到身体的所有细胞中。

When a person exhales or breathes out everything will happen in reverse. The diaphragm relaxes and the lungs become smaller. The cells in the body have received the oxygen it needs, but carbon dioxide must leave the body. This time, wastes enter the alveoli through the capillaries, back through the bronchioles and bronchi, and then the trachea and out through the nose and mouth. The air is warm because it heats up as it travels through the body.

当一个人呼气或吐气则一切相反。隔膜松弛，肺部变小。体内的细胞已接收其所需的氧气，但二氧化碳必须排出身体。此时，废物通过毛细血管进入肺泡，并回到细支气管和支气管，然后通过气管、鼻子和嘴排除。呼出的空气因为穿过体内而变得温暖。

Finally, the lungs are also important for talking. The larynx is located above the trachea, which is often called the voice box. Vocal cords across the larynx open and close, and then vibrate, to create the sounds as air flows between them. The amount of air exhaled determines the loudness of a sound.

最后，肺部对于发声也很重要。喉位于气管，这一部分也被称为喉头。喉头的开合以及声带的振动使得其间的空气以及人体发声。呼出的空气的量决定了声音的响度。

In summary, there are many parts of the respiratory system working together to distribute oxygen throughout the body, as well as the lungs being necessary for a person's ability to talk. It is important to keep the lungs healthy and strong.

呼吸系统是许多器官协同作用将氧气分散到身体的各个部分，而肺也是一个人发声的重要器官。保证肺部的健康和强大是非常重要的。