Blood vessels are fundamental components of the cardiovascular system, responsible for the dynamic transport of nutrients and blood products to every cell in the body. The vascular network begins at the outlets of the heart, runs throughout the body, and returns through the main venous inlets of the heart. This complex vascular highway works to transport blood cells, nutrients, oxygen, and pharmacological agents to the tissues. Just as blood vessels direct material into tissue, they also facilitate the removal of cellular by-products, carbon dioxide, and toxic chemicals from tissue. Histologically, the vascular system is divided into macrovasculature and microvasculature. Small blood vessels contribute to fundamental physiological processes, but they often do not attract the attention associated with macrovascular diseases.