DESIGN AND PHYSIOLOGY OF ARTERIES AND VEINS | The Gastrointestinal Circulation

The circulatory system of fish is arranged in series, with the heart pumping venous blood through the gills where it is oxygenated. Most of the blood then enters the dorsal aorta for distribution to various parts of the body. The gastrointestinal tract is supplied with blood via one or more vessels of the major branches of the dorsal aorta. In elasmobranchs, the branching pattern resembles the mammalian system with at least three distinct vessels, arterial coeliaca, arteria mesenterica superior, and arteria mesenterica inferior, while in most teleosts the gastrointestinal tract is supplied via a single vessel, arteria coeliacomesenterica, which then branch to supply the entire vascular bed. In the fasting, undisturbed fish around 30–40 % of total cardiac output ( Q ) is diverted to the gastrointestinal tract. The gastrointestinal tract is not a prioritized vascular bed in most species studies,…, which means that when the oxygen demand increases in other tissues such as locomotory muscle, gastrointestinal blood flow is temporarily downregulated in order to optimize the oxygen delivery to other organs with a higher priority.