Blodkärlsvägg

Blodkärlsvägg refers to the wall of a blood vessel. These walls are essential for maintaining blood pressure, directing blood flow, and preventing excessive bleeding. The structure of the blood vessel wall varies depending on the type of vessel. Arteries and veins have a similar three-layered structure, while capillaries have a much simpler wall.

The outermost layer is the tunica externa, also known as the tunica adventitia. This layer is composed of connective tissue and provides structural support to the vessel. It contains elastic fibers and collagen, which help the vessel withstand pressure changes.

Beneath the tunica externa lies the tunica media. This is the thickest layer in arteries and is primarily composed of smooth muscle and elastic fibers. The smooth muscle allows the vessel to constrict or dilate, regulating blood flow and pressure. The elastic fibers enable the vessel to stretch and recoil with each heartbeat. In veins, the tunica media is thinner and contains less smooth muscle and elastic tissue compared to arteries.

The innermost layer is the tunica intima. It consists of a single layer of endothelial cells, which form a smooth surface to minimize friction for blood flow. This layer also plays a role in regulating vascular tone and preventing blood clot formation. In arteries, the tunica intima also contains an internal elastic lamina, a layer of elastic tissue that separates it from the tunica media.

Capillaries are the smallest blood vessels and have the simplest wall structure, consisting only of a tunica intima (endothelium) and a basement membrane. This thin wall facilitates the exchange of oxygen, nutrients, and waste products between the blood and the surrounding tissues. The integrity of the blood vessel wall is crucial for cardiovascular health.