Unlike the skeletal muscles, the body's cardiac and smooth muscles are managed by the autonomic nervous system beyond our direct control.

与骨骼肌不同，身体的心肌和平滑肌是由自动神经系统控制，而非听从我们的直接控制。

Your autonomic system is the branch of your peripheral nervous system that regulates the functions of your internal organs, like your heart and stomach, and also controls your smooth and cardiac muscles, and your glands.

你的自主神经系统是你周围神经系统的分支，它调节你内部器官的功能，比如你的心脏和胃，也控制你的平滑肌和心肌，以及你的腺体。

Cardiac muscles are found in the heart and are used only to circulate blood. They have some characteristics of both skeletal and smooth muscles.

心肌存在于心脏且只在血液循环中发挥作用。它们同时具有骨骼和平滑肌的一些特征。

One way an artery can actively resist blood flow is by contracting the smooth muscle in its wall, causing the artery to constrict.

动脉可以主动抵抗血液流动的一种方法是收缩其壁中的平滑肌，使动脉收缩。