32 Fighting Infection!-High

Fighting Infection! FOCUS Question How do cells in your body work together to fight disease?

对抗感染!你体内的细胞是如何协同工作来对抗疾病的?

The Battle Inside Our Bodies Our bodies repel invaders from the moment we are born. Our skin has special cells that protect and warn us about threats. Mucous membranes in the mouth, throat, eyes, lungs, and bowels provide a formidable barrier. But viruses, bacteria (see cover), fungi, and parasites sometimes get through. We ingest them in food and water. They enter our body through cuts and wounds. In one day, we might get a million unwanted, microscopic visitors. We cannot block every intruder, no matter how hard we try. Every day is a battle. Yet it mostly goes unnoticed. Credit your immune system for this. This immune system includes the organs, tissues, and cells that defend against unseen threats.

从我们出生的那一刻起，我们的身体就开始排斥入侵者。 我们的皮肤有特殊的细胞来保护和警告我们威胁。 口腔、喉咙、眼睛、肺和肠道的粘膜提供了一个强大的屏障。 但病毒、细菌(见封面)、真菌和寄生虫有时也会通过。 我们通过食物和水摄入它们。 它们通过伤口进入我们的身体。 在一天之内，我们可能会有一百万个不受欢迎的微生物访客。 无论我们如何努力，我们都无法阻止每一个入侵者。 每天都是一场战斗。然而，这在很大程度上没有引起人们的注意。 这要归功于你的免疫系统。 这个免疫系统包括抵御看不见的威胁的器官、组织和细胞。

Infection Frontlines Has your doctor ever pressed on your neck when you were sick? Inside your neck are lymph nodes. Lymphatic fluid moves throughout the body to screen out invaders. When your lymph nodes are swollen, your immune system is working, probably fighting infection. Your lymphatic system is home to white blood cells, the helpful frontline warriors of the immune system. The lymphatic system works with the circulatory system to help fight infection. The blood stream carries millions of white blood cells throughout the body. There are many types of white blood cells, each with a special job.

你生病的时候，你的医生有没有按过你的脖子? 在你的颈部有淋巴结。 淋巴液在全身流动以排除入侵者。 当你的淋巴结肿大时，你的免疫系统正在工作，可能是在对抗感染。 淋巴系统是白细胞的家园，白细胞是免疫系统的前线战士。 淋巴系统与循环系统协同工作，帮助对抗感染。 血液携带着数百万个白细胞遍布全身。 白细胞有很多种，每一种都有特殊的功能。

On the Attack! Neutrophils (NEW-troh-fills) are white blood cells that seek out and consume viruses, bacteria, and other foreign cells. The neutrophil is first on the scene at an infection site. T lymphocytes (LIM-foh-sites), or T cells, coordinate the other white blood cells. Helper T cells signal the immune system to combat an infection; killer T cells patrol the body and "kill," or eliminate, infected cells. Both types are important for keeping you healthy. Macrophages (MAK-row-fage-is) are the largest white blood cells. They clean up destroyed cells and debris.

进攻中!中性粒细胞(NEW-troh-fills)是白细胞，可以寻找并消耗病毒、细菌和其他外来细胞。 中性粒细胞首先出现在感染部位。 T淋巴细胞(LIM-foh-sites)，或T细胞，协调其他白细胞。 辅助性T细胞向免疫系统发出对抗感染的信号;杀手T细胞在体内巡逻，“杀死”或消灭受感染的细胞。 这两种类型对保持健康都很重要。 巨噬细胞(mako -row-fage-is)是最大的白细胞。 他们清理被破坏的细胞和碎片。

Remembering an Infection B lymphocytes, or B cells, are white blood cells that are the memory of the immune system. B cells identify an invader within the immune system. They target the invader for destruction by making antibodies for that specific infection. Antibodies are proteins that attach to specific invaders. If the infection returns, B cells call in the antibodies from their records. The antibodies do not kill the invaders, but rather put a target on them to mark them for destruction by other cells. T cells then arrive to destroy the targeted foreign invaders. Once an antibody is created, B cells can make new antibodies quickly if the invader returns. Word Wise The term "B cells" begins with a B because these cells grow in bone marrow, a part of the immune system.

B淋巴细胞，或B细胞，是一种白细胞，是免疫系统的记忆。 B细胞在免疫系统内识别入侵者。 它们通过制造针对特定感染的抗体来消灭入侵者。 抗体是附着在特定入侵者上的蛋白质。 如果感染复发，B细胞会从它们的记录中调用抗体。 抗体并不杀死入侵者，而是在它们身上设置一个目标，标记它们，以便被其他细胞破坏。 然后T细胞到达摧毁目标外来入侵者。 一旦产生抗体，如果入侵者回来，B细胞就能迅速产生新的抗体。 “B细胞”一词以B开头，因为这些细胞生长在骨髓中，骨髓是免疫系统的一部分。

Immunity The role of B cells explains how vaccinations prevent disease. A vaccine introduces the body to an invader in a way that doesn't make a person sick. Vaccines are made from dead or weakened versions of an invader. By deliberately exposing the body to the dead or weakened invader, the immune system gets a head start at antibody production. If the real invader ever comes along, B cells are ready to produce antibodies and protect the person from attack. The idea behind vaccines came from Edward Jenner. He knew that people who were exposed to a mild form of smallpox suffered no harm when exposed to the stronger version. Today, we call this immunity. Immunity means that you are protected against a certain disease.

B细胞的作用解释了接种疫苗如何预防疾病。 疫苗以一种不会让人生病的方式将身体引入入侵者。 疫苗是由死的或弱化的入侵者制成的。 通过故意将身体暴露在死亡或虚弱的入侵者面前，免疫系统在抗体产生方面领先一步。 如果真正的入侵者出现，B细胞就会随时产生抗体，保护人不受攻击。 疫苗背后的想法来自爱德华·詹纳。 他知道感染了轻微天花病毒的人在感染了更严重的天花病毒时不会受到伤害。 今天我们称之为豁免权 免疫是指你对某种疾病有免疫力。