心肌结构与收缩心肌纤维是由心肌细胞所组成。心肌细胞的外围是一层薄的细胞膜,即肌纤维膜,膜内有细胞浆与细胞核,在细胞浆中有一些重要的亚细胞结构,如肌原纤维、线粒体、内质网等。1、肌原纤维是心肌的的收缩部分,功能上十分重要。普通显微镜观察,可见肌原纤维是由明暗不同的带组成,较暗的称A带,在A带中间有 Myocardial structure and contraction Myocardial fibers are composed of cardiomyocytes. The outer periphery of cardiomyocytes is a thin cell membrane called myofibrillar membrane, which contains cytoplasm and nucleus. There are some important subcellular structures in the cytoplasm, such as myofibrils, mitochondria and endoplasmic reticulum. 1, myofibril is a part of myocardial contraction, functionally important. Ordinary microscopic observation shows that myofibrillar is composed of different light and dark bands, darker, said A band in the middle of A band