微循环常指通过小血管的血流,它包括细动脉、终末细动脉、毛细血管网、毛细血管后静脉和细静脉。它们既是循环的通路,又是物质交换的场所;形态上既有一般脉管的共性,而排列、形态和结构特征又随脏器而各异。肺是体内最大的、不受支持的血管床,这里所说的不受支持是与肝、脾等实质器官相比较而言 Microcirculation refers to the blood flow through the small vessels, which include the arterioles, the terminal fine arterioles, the capillary network, the post-capillary venules, and the fine veins. They are not only circular pathways, but also places for the exchange of matter. In their morphology, there are not only the common features of the vessels, but also the arrangement, morphology and structural features of the vessels. Lung is the largest, unsupported vascular bed in the body. What is not supported here is compared with the real organs such as liver and spleen