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2.2 微循环的改变 在休克时微循环发生改变,其改变与临床表现及休克的分期有明显的关系.现简述如下:2.2.1 微循环的组成 微循环由下述血管组成:①微动脉 由内皮细胞、平滑肌及结缔组织组成.其收缩与舒张受神经及体液因素支配.在收缩时,外围阻力增加,血压升高.故又称阻力血管.②毛细血管前括约肌 此为调节毛细血管的血流.其收缩与松驰受神经及体液因素支配.③毛细血管 此为一单层上皮,其关闭与开放只受体液因素支配,为血管内外营养物质及废物交换的地方,故又称营养血管.④微静脉 其收缩及舒张主要受血管活性物质支配.当舒张时可以容纳大量的血液,故又称容量血管.⑤动——静脉短路 为微动脉与微静脉之间的短路.2.2.2 微循环血流的通路 在微动脉及微静脉之间有三条通路.①直捷通路 血液自微动脉经过通毛细血管而进入微静脉.通毛细血管为后微动脉的延伸,直径较真毛细血管粗,此通路不进行物质交换,通常处于开放状态,有利于一部份血迅速回到静脉而达心脏.②迂回
2.2 microcirculation changes in the microcirculation changes in shock, the change and clinical manifestations and the staging of shock has a clear relationship is summarized as follows: 2.2.1 The composition of microcirculation Microcirculation consists of the following blood vessels: ① arteries By the endothelial cells, smooth muscle and connective tissue composition.The contraction and relaxation are subject to neurological and humoral factors in the contraction, the peripheral resistance increased, elevated blood pressure.Therefore, also known as the resistance of blood vessels.Pre-capillary sphincter This is the regulation of capillaries Blood flow whose contraction and relaxation are dominated by neurological and humoral factors.③ This is a monolayer of capillaries, which is closed and open only by humoral factors, which is also known as the exchange of nutrients and wastes inside and outside the blood vessels Nutrient vessels .④ venules its contraction and relaxation dominated by vasoactive substances .When diastolic can accommodate a lot of blood, it is also called the capacity of blood vessels .⑤ arteriovenous short circuit between the micro-arteries and venules short circuit.2.2 .2 Microcirculation Blood Flow Pathways There are three pathways between the arterioles and the venules. ① Direct access blood flows through the capillaries and into the venules through the arterioles. Extending arteries, capillaries seriously rough diameter, this pathway is not material exchange, typically in an open state, a beneficial part of the venous blood return to the heart quickly .② detour