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体育的功能之一是清醒头脑,人在学习思考时,大脑神经细胞处于积极紧张活动状态,需要大量的能源物质,如血糖、蛋白质、脂肪等,还需要大量的氧气。这些东西是靠血液循环源源不断地运输,并带走大脑神经细胞活动时所产生的代谢物,如乳酸、丙酮酸、二氧化碳。人脑处于安静状态时,脑部的血流量相当于一个人心输出量的六分之一左右;人脑在紧张思考时,所需要的血流量比平常要大15——25倍。可见,只靠心脏来维持血液循环是完不成任务的,还必须靠肌肉系统的支持,肌肉放松时,里面充满血液,肌肉收缩时,血液挤向心脏和心脏的功能完全一致。经常从
One of the functions of sports is to clear the mind. When people are learning to think, the brain cells are in a state of active nervous activity. They need a lot of energy substances, such as blood sugar, protein, and fat, and they also need a lot of oxygen. These things are continuously transported by the blood circulation and take away metabolites produced when the brain’s nerve cells are active, such as lactic acid, pyruvic acid, and carbon dioxide. When the human brain is in a quiet state, the blood flow in the brain is equivalent to about one-sixth of the output of a human heart; when the human brain is thinking intensely, the blood flow needed is 15 to 25 times larger than usual. Visible, relying solely on the heart to maintain blood circulation is not a task, but also must rely on the muscle system support, muscle relaxation, which is full of blood, muscle contraction, the blood squeezed heart and heart functions exactly the same. Often from