Vein they were for transport of air. The Greek physician, Herophilus, distinguished veins from arteries but thought that the pulse was a property of arteries themselves. Greek anatomist Erasistratus observed that arteries that were cut during life bleed. He ascribed the fact to the phenomenon that air escaping from an artery is replaced with blood that entered by very small vessels between veins and arteries. Thus he apparently postulated capillaries but with reversed flow of blood. In 2nd century AD Rome, the Greek physician Galen knew that blood vessels carried blood and identified venous (dark red) and arterial (brighter and thinner)
Mesenteric arteries smaller mesenteric vessels, the resistance of blood flow to the gut increases, and hence blood flows more readily to other organs. Mesenteric arteries The mesenteric arteries take blood from the aorta and distribute it to a large portion of the gastrointestinal tract. Both the superior and inferior mesenteric arteries arise from the abdominal aorta. Each of these arteries travel through the mesentery, within which they branch several times before reaching the gut. In humans, many of these branches are named, but in smaller animals the branches are more variable. In some animals, including humans, branches of these arteries join with