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初中动物学三年级上学期的课,在讲到两栖类青蛙的时候,其中关于血液循环器官一小节,介绍了两个循环途径:一个是大循环,一个是小循环。这两个血液循环的途径,一般说来,学生比较不容易理解,所以为了给学生建立明确的概念,往往配合直观的教具——蛙的血液循环注射标本,来给学生观察。关于注射的方法,一般都在主动脉处注射红色膠液(或淀粉液)腹大静脉处注入蓝色胶液,可是其中困难最大处就是用棉线穿过动脉圆锥,扎结此处,使隔绝心室与主动脉的相通,以免色液倒流。因为动脉圆锥与心室间有薄膜粘连,如果没有熟练的技术,往往不是把动脉管穿破,就是把静脉窦刺破,以致血液流出,标本损失。我们开始做的时候就遭到了这样的结果,后来我们发现如果不穿棉綫而用血管钳钳住主动脉干下部,同样
Junior high school zoology third semester last semester class, when it comes to amphibians frogs, of which a section on the blood circulation organs, introduced two cycles: one cycle, one is a small cycle. The two methods of blood circulation, in general, students are not easy to understand, so in order to establish a clear concept for students, often with intuitive teaching aids - frog blood circulation injection specimens to students. About the injection method, usually in the aorta injection of red glue (or starch solution) ventral large venous injection of blue glue, but the most difficult of which is the use of cotton thread through the arterial cone, tied here, so isolated Ventricular and aorta communication, in order to avoid color liquid back. Because of arterial conization and ventricular thin-film adhesion, if there is no skilled technique, often not the arterial puncture, is to puncture the sinus, resulting in blood flow out, the specimen loss. When we started doing so, we got such a result. Later on, we found that if we did not wear cotton thread and forceps to clamp the lower part of aorta,