Germs are all around us, both in our environment and in our bodies.
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一个易感的人如果遇到有害生物，便可能因此患病和死亡。
When a person is susceptible and they encounter a harmful organism, it can lead to disease and death.
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人体有许多防御病原体（致病生物）的方法。
The body has many ways of defending itself against pathogens (disease-causing organisms).
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皮肤、粘液和纤毛（将碎屑从肺部移除的微小毛发）都可充当物理屏障，首先防止病原体进入身体。
Skin, mucus, and cilia (microscopic hairs that move debris away from the lungs) all work as physical barriers to prevent pathogens from entering the body in the first place.
When a pathogen does infect the body, our body’s defences, called the immune system, are triggered and the pathogen is attacked and destroyed or overcome.
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身体的自然反应
The body's natural response
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病原体是一种细菌、病毒、寄生虫或真菌，可在体内引起疾病。
A pathogen is a bacterium, virus, parasite or fungus that can cause disease within the body.
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每种病原体都由几个部分组成，通常是特定病原体及其引起的疾病所特有的。
Each pathogen is made up of several subparts, usually unique to that specific pathogen and the disease it causes.
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病原体中导致抗体形成的部分被称为抗原。
The subpart of a pathogen that causes the formation of antibodies is called an antigen.
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针对病原体的抗原产生的抗体是免疫系统的重要组成部分。
The antibodies produced in response to the pathogen’s antigen are an important part of the immune system.