The apical or upper side, is exposed to either the outside of your body, or whatever internal cavity it's lining.

顶端或上部，暴露在身体外部或它任何内腔中。

This causes a decreased blood flow through its lumen, or hollow center.

这导致通过其内腔或中空中流减少。

Most of your blood vessels share a similar structure consisting of three layers of tissue surrounding the open space, or lumen, that actually holds the blood.

大多数管都有一个相似结构，由三层组织组成，围绕着开放空间或内腔，实际上容纳液。

Anatomists call these layers " tunics, " and the innermost section is the tunica intima — which should be pretty easy to remember because, you know, it has like intimate contact with the lumen. It's like your circulatory underpants.

剖家称这些层为束腰外衣，最里面部分是内膜——这应该很容易记住，因为，知道，它和内腔有亲密接触。就像循环内裤。