初中《生理卫生》第四章有关血液循环的内容中提到:血管中的一滴血通过一条完整的循环途径约需20多秒.这一数据有待推敲.人体内的肺循环与体循环这两条途径通过心脏连通在一起,成为人体内的一条完整的循环途径.当血液从左心室出发,再回到左心室时,血液正好走完这两条循环途径.人在安静状态下,血液在人体内循环一周所经历的时间 The fourth chapter of “physiological hygiene” in junior high school about blood circulation mentioned that: a blood drop in a blood vessel takes about 20 seconds through a complete circulation route. This data needs to be deduced. Pulmonary circulation and systemic circulation in the human body are two ways. Connected by the heart, it becomes a complete circulation path in the human body. When blood starts from the left ventricle and returns to the left ventricle, the blood just goes through these two circulation pathways. In the quiet state, the blood is in the human body. Cycle time