双语字幕
Blood vessels - Structure & Function
血管的结构与功能
Blood vessels carry blood around the body. Oxygenated blood exits the heart from the aorta and passes into the artery.
血管将血液输送到全身。富氧血液通过主动脉流出心脏，进入动脉。
The artery walls consist of three layers.
动脉壁由三层组成。
The tunica adventitia is the strong outer covering which consists of connective tissues, collagen, and elastic fibers.
血管外膜是由结缔组织、胶原纤维和弹性纤维组成的坚固外层。
The tunica media is the middle layer and consists of smooth muscle and elastic fibers which enable it to constrict and dilate.
中膜是中间层，由平滑肌和弹性纤维组成，因此，血管能够收缩和扩张。
The Tunica intima is the inner layer which is in direct contact with the blood flowing through the artery. It consists of an elastic membrane and smooth endothelial cells.
内膜是血管内层，与通过动脉的血流直接接触。它由弹性膜和光滑的内皮细胞组成。
The hollow Center through which blood flows is called the lumen. Arteries split into smaller vessels called arterioles, and eventually into capillaries which are the smallest blood vessels.
血液流经的中空中心称为管腔。动脉分支为更小的血管--小动脉，最终分支为毛细血管，而毛细血管是人体内最小的血管。
Unlike veins and arteries, the main function of capillaries is not transporting blood. They are specially designed to allow the movement of oxygen, carbon dioxide, and other nutrients, to and from the surrounding tissues.
毛细血管不同于静脉和动脉，其主要功能不是输送血液。毛细血管是周围组织发生氧气、二氧化碳和其他营养物质交换的主要场所。
Capillaries have very thin walls comprised only of endothelial cells. This allows substances to move through the cell wall with ease.
毛细血管壁非常薄，仅由内皮细胞组成。因此，物质能够很容易地穿过细胞壁。
Veins are blood vessels that carry deoxygenated blood back to the heart.
静脉是将脱氧血液输送回心脏的血管。
Capillaries drain blood into very small veins called venules. These merge into larger vessels and eventually into veins.
毛细血管将血液排入非常小的静脉--小静脉中。小静脉融合成更大的血管，最终形成静脉。
The structure of veins is similar to that of arteries, again consisting of three layers.
静脉的结构与动脉相似，同样由三层组成。
The tunica adventitia is the strong outer covering. The tunica media is the middle layer consisting of smooth muscle and elastic fibers. This layer is thinner in veins than in arteries.
外膜是坚固的外层。中膜是由平滑肌和弹性纤维组成的中间层。静脉的中膜比动脉的中膜薄。
The Tunica intima is the inner layer which is in direct contact with the blood flowing through the vein. It consists of smooth endothelial cells and a hollow center called the lumen through which blood flows.
内膜是与流经静脉的血液直接接触的内层。它由光滑的内皮细胞和血液流经的称为管腔的中空中心组成。
Veins also contain valves that prevent backflow of blood and aid venous return.
静脉也含有防止血液回流和帮助静脉回流的瓣膜。
相关单词学习
Adventitia
①发音和释义
ad•ven•ti•ti•a/ˌædvenˈtɪʃiə/n. 【解】外膜
The external covering of an organ or other structure, derived from connective tissue, esp. the external covering of a blood vessel.
tunica adventitia 外膜层
形容词adventitial/ædvən'tɪʃl/adj. 外膜的
- （图源：太帅图库）
Venule
ven•ule/'venjul/n. 小静脉
A small vein.
单词 venule 由下列成分构成
vein 静脉
+
-ule（后缀）表示“小”
（来源：太帅图库）
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