人体在活动时需要进行能量物质的氧化,氧的供应是实现人体正常活动必不可少的物质条件,因而人体不断地从外界环境中摄取氧同时又排出二氧化碳。氧气的进入和二氧化碳的排出是依据人体吸气肌对胸廓的作用,引起肋的上提运动,膈的运动,造成胸腔体积的扩大,氧气由呼吸道进入肺最终入血液。与此同时,血液中的二氧化碳进入肺,又 The human body needs the oxidation of energy substances during the activity. The supply of oxygen is an essential material condition for the normal activities of the human body. Therefore, the human body constantly absorbs oxygen from the external environment and emits carbon dioxide at the same time. Oxygen intake and carbon dioxide emissions are based on the role of the human inspiratory muscle on the thorax, causing the ribs on the move, the diaphragm movement, resulting in the expansion of the chest cavity, oxygen from the respiratory tract into the lungs and eventually into the bloodstream. At the same time, carbon dioxide in the blood enters the lungs, again