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。
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