Anatomy of the Human Body. Henry Gray (1. 82. NORMAL VENOUS CIRCULATION. The heart and the blood vessels are the most important parts of the circulatory system. The Veins Introduction THEVEINS convey the blood from the capillaries of the different parts of the body to the heart. They consist of two distinct sets of vessels, the pulmonary and systemic. This vessel ramifies in the substance of the liver and there breaks up into a minute network of capillary- like vessels, from which the blood is conveyed by the hepatic veins to the inferior vena cava. The branches arising from these plexuses unite together into trunks, and these, in their passage toward the heart, constantly increase in size as they receive tributaries, or join other veins. The veins are larger and altogether more numerous than the arteries; hence, the entire capacity of the venous system is much greater than that of the arterial; the capacity of the pulmonary veins, however, only slightly exceeds that of the pulmonary arteries. The veins are cylindrical like the arteries; their walls, however, are thin and they collapse when the vessels are empty, and the uniformity of their surfaces is interrupted at intervals by slight constrictions, which indicate the existence of valves in their interior. They communicate very freely with one another, especially in certain regions of the body; and these communications exist between the larger trunks as well as between the smaller branches. Thus, between the venous sinuses of the cranium, and between the veins of the neck, where obstruction would be attended with imminent danger to the cerebral venous system, large and frequent anastomoses are found. The same free communication exists between the veins throughout the whole extent of the vertebral canal, and between the veins composing the various venous plexuses in the abdomen and pelvis, e. With the smaller arteries—as the radial, unlar, brachial, tibial, peroneal—they exist generally in pairs, one lying on each side of the vessel, and are called ven. The larger arteries—such as the axillary, subclavian, popliteal, and femoral—have usually only one accompanying vein. In certain organs of the body, however, the deep veins do not accompany the arteries; for instance, the veins in the skull and vertebral canal, the hepatic veins in the liver, and the larger veins returning blood from the bones. PDF File: Human Body Veins And Arteries - HBVAAPDF-WWRG15-5 2/4 Human Body Veins And Arteries INTRODUCTION This particular Human Body Veins And Arteries PDF start with Introduction, Brief Session till the Index/Glossary page. Body, leg veins have the toughest job of. They endure the most pressure. The doctor uses a needle to inject a liquid chemical into the vein. Explore the anatomy of the human cardiovascular system. As skeletal muscles in the body contract, they squeeze nearby veins and push.
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January 2017
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