What is the definition of tunica intima?

The tunica intima is accurately defined as the inner lining of the arterial wall. It plays a crucial role in vascular health and function as it consists of a smooth layer of endothelial cells, which helps to minimize friction between the blood and the vessel wall, facilitating smooth blood flow. This layer is in direct contact with the blood and is significant for regulatory functions, including the modulation of vascular tone and inflammation.

The tunica intima, being the innermost layer, contrasts with the other layers of arterial walls, such as the tunica media, which is the middle layer primarily made up of smooth muscle, and the tunica externa (or adventitia), which is the outer layer composed of connective tissue. Understanding the structure and function of the tunica intima is essential for comprehending overall vascular dynamics and potential pathological conditions that can affect blood vessels.