27 The Human Body-Mid

The Human Body Written by Kira Freed

《人体》作者:基拉·弗里德

Introduction Your body is like a busy city. A city has homes, stores, streets, a power station, and much more. Like a city, your body has many systems that work together to keep you alive. The systems are working all the time, and they all need to stay healthy to do their jobs. Do You Know? Check your knowledge before reading this book. What do you know about each of the ten systems in your body? skeletal system muscular system nervous system respiratory system circulatory system digestive system excretory system reproductive system endocrine system immune system

你的身体就像一座繁忙的城市。 城市有住宅、商店、街道、发电站等等。 就像一座城市一样，你的身体有许多系统共同工作来维持你的生命。 这些系统一直在工作，它们都需要保持健康来完成它们的工作。 你知道吗?在阅读这本书之前检查一下你的知识。 你对身体的十个系统都了解多少? 骨骼系统肌肉系统神经系统呼吸系统循环系统消化系统排泄系统生殖系统内分泌系统免疫系统

Every minute of your life, your heart pumps blood through your body. Messages move to and from your brain, and your lungs carry oxygen to cells. Your body kills bad germs, controls your temperature, and gets rid of waste products. It also does thousands more jobs— even while you are sleeping! In this book, you will learn about seven important body systems. As you read, think about all the jobs each body system does to keep you alive and healthy.

生命中的每一分钟，你的心脏都在向全身输送血液。 信息在你的大脑之间来回传递，你的肺将氧气输送到细胞。 你的身体会杀死有害细菌，控制体温，排出废物。 它还可以做成千上万的工作——甚至在你睡觉的时候!在这本书中，你将了解七个重要的身体系统。 当你阅读时，想想每个身体系统为保持你的生命和健康所做的所有工作。

The Skeletal System The bones of your skeletal system support the rest of your body. Like the steel beams inside the walls of buildings, they support all the other systems. Without bones, you would be a mushy blob! Bones also help you to move, and they protect your organs. Your spine, the main support, is a long column of twenty-six bones. Your skull protects your brain from getting hurt. Your ribs wrap around your chest, protecting your heart and lungs. Your pelvis helps to protect the organs in your belly.

骨骼系统骨骼系统的骨骼支撑着身体的其他部分。 就像建筑物墙壁内的钢梁一样，它们支撑着所有其他系统。 没有骨头，你就是一团糊状的东西!骨头也帮助你移动，保护你的器官。 你的脊椎是主要的支撑，是由26块骨头组成的一根长柱。 你的头骨保护你的大脑不受伤害。 你的肋骨环绕着你的胸部，保护你的心脏和肺。 骨盆有助于保护腹部的器官。

Long, strong bones support your arms and legs. Your hands, wrists, feet, and ankles have many smaller bones. Each of the 206 bones in your body has a special job. Did you realize your bones are alive? Bones are made of living cells. This is why bones grow. Spongy stuff in the center of bones, called bone marrow, makes new blood cells. Do You Know? Can you guess where the smallest bones in your body are? They're in your middle ears! Three tiny bones carry vibrations from your eardrums to your inner ears.

又长又壮的骨头支撑着你的胳膊和腿。 你的手、手腕、脚和脚踝有很多小骨头。 人体206块骨头中的每一块都有特殊的功能。 你意识到你的骨头是活的吗? 骨头是由活细胞构成的。 这就是骨头生长的原因。骨骼中心的海绵物质，叫做骨髓，可以制造新的血细胞。 你知道吗?你能猜到你身体里最小的骨头在哪里吗? 它们在你的中耳里!三个小骨头将振动从耳膜传递到内耳。

The Muscular System The muscular system works with the skeletal system so you can move. Unlike other body tissues, your muscles can contract (become shorter and tighter) or relax (become longer and looser). The muscles that bend your joints work in pairs. When one contracts, its partner relaxes. Then they switch jobs. Your body has three different types of muscles— skeletal, smooth, and cardiac. Wowser! Your body has more than 650 muscles! Almost half your weight is muscles.

肌肉系统肌肉系统与骨骼系统协同工作，你才能活动。 与其他身体组织不同，你的肌肉可以收缩(变短变紧)或放松(变长变松)。 弯曲关节的肌肉是成对工作的。 当一方收缩时，另一方放松。 然后他们换工作。你的身体有三种不同类型的肌肉——骨骼肌肉、光滑肌肉和心脏肌肉。 老古板!你的身体有650多块肌肉!你的体重几乎一半是肌肉。