INBDE Practice Exam 2026 – Complete Study Guide

The Tunica Adventitia layer, also known as the Tunica Externa, provides structural support and protection for the veins. In contrast, the Tunica Media, Tunica Intima, and Endothelium layers are thinner and do not provide as much structural support. The Tunica Media is mainly responsible for regulating vessel diameter, while the Tunica Intima and Endothelium function in maintaining the inner lining of blood vessels. Therefore, the Tunica Adventitia is thicker in veins to provide additional support for the walls of these vessels, which must withstand lower blood pressure compared to arteries.