The arterial system has thicker muscle walls since within arteries the blood circulates under higher pressure. The veins are more flaccid than arteries. From the lumen to the external layer both types of vessels are made of endothelium, muscle tissue and connective tissue. In both the endothelium is a single layer of cells. In arteries the muscle tissue portion is thicker than in veins and in these vessels the external connective tissue is thicker than in arteries. Arteries are the pulsating blood vessels. The arterial pulse can be felt in a medical examination, for example, by the palpation of the radial artery in the internal and lateral face of the wrist near the base of the thumb. The Circulatory System - Image Diversity: artery histology vein histology