兽医产科学 第五章 分娩ppt课件

increase of estrogen level stimulate the uterus synthesize the receptor of oxytocin and secrete prostaglandin.Р二、分娩的机理Р分娩启动是各种因素共同作用的结果。?胎儿的丘脑下部-垂体-肾上腺轴系统与分娩的启动密切相关。正常分娩之前,胎儿发育成熟,垂体分泌大量ACTH,使肾上腺皮质醇的含量增多。引起孕酮分泌减少和雌激素分泌增多。孕酮水平下降,解除了对子宫的抑制作用。雌激素水平增加,刺激子宫合成催产素受体和分泌前列腺素。РWhen the fetus and gestational sac are pushed to cervix, the front part stimulate nerve ceptor of cervix and vagina, promote oxytocin release, which produces the expulsion force of the abdominal straining. The oxytocin amount released and intensity of abdominal straining relate to the intensity of stimulation to nerve ceptor, every abdominal straining could lead to more intensive one next timeР当胎儿及胎囊部分被逐渐地推到子宫颈口时,胎囊及胎儿前置部分强烈刺激子宫颈及阴道的神经感受器,反射性的使母体垂体释放催产素增多,引起腹肌和膈肌发生努责。催产素的释放量和努责的强度与子宫颈与阴道的神经感受器受刺激的强度有关,每一次阵缩和努责都会引发下一次更为强烈的阵缩和努责。