What are the walls of aorta made of?

The walls of the aorta are made of three layers:

1. Tunica intima: The innermost layer of the aorta, the tunica intima, is composed of a single layer of endothelial cells that lines the lumen of the vessel. These cells are responsible for maintaining the blood-tissue barrier and producing vasodilator substances such as nitric oxide (NO).

2. Tunica media: The tunica media is the middle layer of the aorta and is made up of smooth muscle cells arranged in concentric layers. These cells are responsible for regulating the diameter of the vessel by contracting and relaxing. The tunica media also contains elastin fibers that provide elasticity and recoil to the vessel.

3. Tunica adventitia: The outermost layer of the aorta is the tunica adventitia, which is composed of connective tissue and contains fibroblasts, collagen fibers, and vasa vasorum (small blood vessels that supply the aorta). The tunica adventitia provides support and protection to the vessel.