Figure 3.

Diagram depiction of systemic blood vessels demonstrating blood flow from an artery to an arteriole, venule, and vein. The blood–brain barrier (BBB) is found at the level of the capillaries within the brain and is not present in normal circulation. Although most of the focus on BBB changes following TBI has focused on capillaries, a growing body of evidence is supporting the importance of small venules distal to the arterial and capillary circulation. No evidence has yet demonstrated leakiness at the level of the arterioles.¹²²