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  • 肌肉

    A man lifting a dumbbell while seated, showcasing his muscular bicep.

    What exactly are muscles?
    ::什么是肌肉?

    Does the word "muscle" make you think of the biceps of a weightlifter, like the man in the picture above? Muscles such as biceps that move the body are easy to feel and see, but they aren’t the only muscles in the . Many muscles are deep within the body. They form the walls of internal organs such as the heart and stomach . You can flex your biceps like a body builder, but you cannot control the muscles inside you. It’s a good thing that they work on their own without any conscious effort on your part, because movement of these muscles is essential for survival.
    ::“肌肉”一词是否让你想到一个举重器的二头肌,像上面的图片中的人那样?象移动身体的二头肌这样的肌肉很容易感觉和看到,但并不是唯一的肌肉。许多肌肉在身体内深处。它们形成心脏和胃等内脏的墙壁。你可以像身体建筑师一样伸展你的二头肌,但你无法控制你体内的肌肉。它们自己工作是一件好事,没有你的任何自觉的努力,因为这些肌肉的移动对于生存至关重要。

    What Are Muscles?
    ::什么是肌肉?

    The muscular system consists of all the muscles of the body. Muscles are composed mainly of muscle , which are also called muscle fibers . Each muscle fiber is a very long, thin cell that can do something no other cell can do. It can contract, or shorten. Muscle contractions are responsible for virtually all the movements of the body, both inside and out. There are three types of muscle tissues in the human body: cardiac, smooth, and tissues . They are shown in Figure and described below.
    ::肌肉系统由身体的所有肌肉组成。肌肉主要由肌肉组成,这些肌肉也称为肌肉纤维。每个肌肉纤维是一个非常长的、薄的细胞,可以做其他细胞无法做的事情。它可以缩缩缩,也可以缩短。肌肉收缩几乎是身体内外所有运动的原因。人体有三种肌肉组织:心脏、光滑和组织。图中显示了这些情况,下文对此作了说明。

     

     

    Three types of muscle tissue: skeletal, smooth, and cardiac, illustrating their structural differences.
    Types of Muscle Tissue. Both skeletal and cardiac muscles appear striated, or striped, because their cells are arranged in bundles. Smooth muscles are not striated because their cells are arranged in sheets instead of bundles.

    Smooth Muscle
    ::平滑肌肉

    Muscle tissue in the walls of internal organs such as the stomach and intestines is smooth muscle . When smooth muscle contracts, it helps the organs carry out their functions. For example, when smooth muscle in the stomach contracts, it squeezes the food inside the stomach, which helps break the food into smaller pieces. Contractions of smooth muscle are involuntary. This means they are not under conscious control.
    ::胃部和肠道等内脏的墙壁上的肌肉组织是光滑的肌肉。当肌肉滑动时,它帮助器官发挥功能。例如,胃部肌肉滑动时,它将食物挤压在胃部,从而帮助食物破碎成小块。肌肉滑动是非自愿的,这意味着它们不受意识控制。

    Skeletal Muscle
    ::骨骼肌肉

    Muscle tissue that is attached to is skeletal muscle . Whether you are blinking your or running a marathon, you are using skeletal muscle. Contractions of skeletal muscle are voluntary, or under conscious control. When skeletal muscle contracts, bones move. Skeletal muscle is the most common type of muscle in the human body.
    ::与骨骼组织相连的肌肉组织是骨骼肌肉。无论你眨眼或跑马拉松,你都会使用骨骼肌肉。骨骼肌肉的缩缩是自愿的,或者在有意识的控制下。当骨骼肌肉结合时,骨骼运动。骨骼肌肉是人体中最常见的肌肉类型。

    Cardiac Muscle
    ::心脏肌肉

    Cardiac muscle is found only in the walls of the heart. When cardiac muscle contracts, the heart beats and pumps . Cardiac muscle contains a great many , which produce ATP for energy . This helps the heart resist fatigue. Contractions of cardiac muscle are involuntary, like those of smooth muscle. Cardiac muscle, like skeletal muscle, is arranged in bundles, so it appears striated , or striped.
    ::心肌只有在心脏的墙壁中才能发现。当心脏肌肉收缩时,心脏跳动和泵。心肌含有许多能产生能量的ATP。这有助于心脏抵抗疲劳。心肌的萎缩是非自愿的,就像光滑的肌肉一样。心肌,像骨骼肌肉一样,被捆绑在捆绑中,所以看起来是被撕裂的,或者被条条纹的。

    Further Reading
    ::继续阅读

    Summary
    ::摘要

    • There are three types of human muscle tissue: smooth muscle (in internal organs), skeletal muscle, and cardiac muscle (only in the heart).
      ::人体肌肉组织有三种类型:光滑肌肉(内脏)、骨骼肌肉和心脏肌肉(只有心脏)。

    Review
    ::回顾

    1. Compare and contrast the three types of muscle tissue.
      ::比较和对比这三种肌肉组织
    2. What can muscle cells do that other cells cannot?
      ::肌肉细胞能做什么 其他细胞不能做?
    3. Why are skeletal and cardiac muscles striated?
      ::为什么骨骼和心肌肌肉分裂?
    4. Where is smooth muscle tissue found?
      ::光滑肌肉组织在哪里找到的?
    5. What is the function of skeletal muscle? Give an example.
      ::骨骼肌肉的功能是什么?举个例子。