题型：阅读选择 题类：模拟题 难易度：普通
江苏省苏州市张家港市2019届中考英语网上阅卷适应性考试试卷
Sometimes our body does things we don't ask it to do. Sneezing(打喷嚏), coughing, blinking(眨眼睛)and even yawning(打哈欠)are examples of involuntary movements or reflex actions(反射动作).What makes our body do these things?
These involuntary actions are a response(反应)to a stimulus(刺激).When we do these things, our body is trying to protect itself. If an irritant(刺激物)such as pollen(花粉)from plants gets into our nose or nasal passages(鼻腔通道),our body sneezes to get it out. If we breathe in dust, our body coughs to remove it from our lungs(肺)or windpipe. We blink in order to keep our eyes clean and moist(湿润)and to prevent dust and other things from staying on them. A yawn is our body's way of making us put more oxygen into our bloodstream.
These involuntary movements happen because our brain is giving out signals.
There is a system of nerves(神经)called the central nervous system, that covers our entire body: from the brain, down the spinal cord(脊位)inside our spinal column (the bones that do down our back, to the tips of our fingers and toes. When' our body parts sense certain things, like a mosquito蚊子)bite, a message is sent to our brain. Then the brain sends a message back to itch(发痒).
Without these reflex actions, we would not live very long.
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