But Sickle Cell Anemia causes the red blood cells to stick together. Then, they can block small veins.

但是镰状细胞贫血会导致红细胞粘在一起。然后，它们会阻塞小静脉。

Next, blood get drained from these spaces by small emissary veins, which drain into the deep dorsal vein.

接下来，血液从这些间隙通过小的导静脉流出，这些血液会流入背深静脉。

Small veins converge to form larger and larger veins, which eventually drain into the venae cavae.

小静脉汇聚形成越来越大的静脉，这些静脉最终排入腔静脉。

And blood pressure in veins is extremely low compared with pressure in arteries. The smallest veins, called venule , are formed by the union of capillaries.

微静脉 壁略厚于毛细血管壁。随着静脉变大，管壁变厚。

The blade of the leaf extends from either side of that big vein, and smaller veins branch off from it that support the leaf and supply it with water and food.

叶子的叶片从大叶脉的两侧延伸出来，小叶脉从叶脉上分支出来，支撑着叶子，为叶子提供水分和食物。