First, they cause vasodilation, which allows more blood to flow through the collateral vessel.

首先，它们导致血管扩张，使通过侧支血管的血流更多。

So with vasodilation of the arterioles, more heat gets lost which, therefore, helps to lower body temperature.

因此，随着动脉血管舒张，更多热量会流失，有助于降低体温。

When you're very relaxed, there tends to be vasodilation.

当你非常放松时，血管往往会舒张。

This leads to vasodilation, or increased blood flow to the blood vessels, ultimately causing an erection.

这会导致血管舒张，或流向血管的血流量增加，最终导致勃起。

Over time, this results in maximal vasodilation beyond the obstruction, and it helps the collateral vessel redivert blood to the ischemic myocardium.

随着时间的推移，这会使阻塞远端的血管最大程度地扩张，并帮助侧支循环将血流引向缺血的心肌。

This causes vasodilation, which decreases total peripheral resistance and decreases blood pressure.

这会引起血管舒张，从而降低总外周阻力并降低血压。

When the artery is in a state of vasodilation, the lumen of the artery gets bigger and blood flow increases.

当动脉处于舒张状态时，动脉管腔变大，血流增加。

Changes in diameter can be temporary, like during vasoconstriction or vasodilation — when the diameter increases or decreases, allowing more or less blood through.

直径的变化可能是暂时的，比如在血管收缩或舒张期间——直径增加或减少，允许或多或少的血液通过。

This allows them to contract or relax through vasoconstriction and vasodilation, which we've talked about a lot in terms of the nervous system's stress response.

这使它们能够通过血管收缩和舒张来收缩或放松，我们已经就神经系统的压力反应谈了很多。

Therefore, if a blood vessel's radius doubles in size due to vasodilation, the blood flow through the vessel will increase 16 fold.

因此，如果由于血管扩张而使血管半径扩大一倍，则流经血管的血液将增加16倍。

This information is relayed to the cardio regulatory center of the medulla, which responds to the high blood pressure by causing decreased heart rate and causing vasodilation.

这些信息被传递到延髓的心脏调节中心，它通过降低心率和引起血管舒张来对高血压做出反应。

If, on the other hand, the smooth muscle in the wall of the artery relaxes, the blood vessel moves into a state of vasodilation, and its lumen dilates, or gets bigger.

另一方面，如果动脉壁上的平滑肌松弛，血管就会进入血管扩张状态，管腔也会扩张或变大。

When the test is done in an individual with coronary artery disease, it results in vasodilation of all coronary arteries, except the ones which are obstructed - because beyond the obstruction, the coronary artery is already maximally dilated.

当一个冠状动脉疾病患者做了这个试验，他所有的冠状动脉都会扩张，除了那根被阻塞的，因为阻塞远端的冠状动脉已经最大程度地扩张了。

That smooth muscle tissue is regulated in part by the nerve fibers of the autonomic nervous system, which can decrease the diameter of the lumen by contracting this middle layer during vasoconstriction, or expand it by relaxing during vasodilation.

平滑肌组织部分由自主神经系统的神经纤维调节，自主神经系统可以在血管收缩时通过收缩中间层来减小管腔直径，或者在血管舒张时通过放松来扩大管腔直径。