Large Artery / Elastic Artery Under the Microscope - скачать в хорошем качестве

Large Artery / Elastic Artery Under the Microscope -

Elastic arteries, the body's largest arteries, are characterized by a highly elastic tunica media that allows them to stretch and recoil with each heartbeat. This histological feature, visible under a microscope, dampens the pulsatile flow of blood from the heart, ensuring a smoother, more continuous blood flow to the rest of the body. The wall of an elastic artery is composed of three distinct layers, or tunics: Tunica intima - This is the innermost layer of the vessel, with the following characteristics: 1. Endothelium: A single layer of flattened, simple squamous epithelial cells lines the lumen, providing a smooth surface for blood flow. 2. Subendothelial layer: Beneath the endothelium is a thin layer of connective tissue containing elastic fibers, collagen, and scattered smooth muscle cells. 3. Internal elastic lamina (IEL): This layer of elastic tissue separates the tunica intima from the tunica media. In elastic arteries, it is often indistinct because it blends with the numerous elastic layers of the tunica media. Tunica media - This is the thick, elastic middle layer that is the defining feature of elastic arteries. 1. Elastic lamellae: It is primarily composed of 40 to 70 layers of concentrically arranged, fenestrated (holed) elastic sheets. 2. Smooth muscle: Thin layers of circularly arranged smooth muscle and collagen fibers are interspersed between the elastic lamellae. 3. External elastic lamina (EEL): In elastic arteries, this layer separating the tunica media and tunica adventitia is often less prominent and can be difficult to distinguish. Tunica externa (adventitia) - This is the outermost layer of the arterial wall. Composition: It consists of fibroblasts, collagen, and elastic fibers that are more loosely organized than in the tunica media. Vasa vasorum: In large vessels like elastic arteries, the tunica externa contains small blood vessels called vasa vasorum ("vessels of vessels") that supply the outer layers of the arterial wall with nutrients and oxygen. Function: This layer provides structural support and anchors the artery to the surrounding tissue.