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Human Blood Circulation and Cardiovascular Circulation - Systemic vs Pulmonary Circulation - hepatic portal vein
Definition of terms (artery, vein, pulmonary artery and pulmonary vein)
Vein: These blood vessels deliver blood from the body tissues to the heart. The characteristics of blood in veins are a high level of carbon dioxide and are therefore deoxygenated.
Artery: These blood vessels lead from the heart to the rest of the body. The blood in arteries is usually oxygenated, means; the red blood cells carry oxygen and deliver the tissues with oxygen.
Pulmonary artery: They are one of the only arteries, which carry deoxygenated blood from the heart to the lung. It begins at the base of the right ventricle and branches into two pulmonary arteries, which go the respective lung taking deoxygenated blood there.
Pulmonary vein: These special veins carry oxygenated blood from the lungs to the left atrium of the heart.
Hepatic portal vein: The hepatic portal vein is not a true vein, since it does not deliver deoxygenated blood directly to the heart. It is a vessel in the abdominal cavity (or gut) and leads to the liver directly. In the abdominal cavity (or gut) the blood quality is deoxygenated blood and on its way to the liver it passes a capillary bed (blood becomes oxygenated, since capillaries are this small that they enable an exchange of molecules between the blood and the surrounding tissue) and takes up solvable molecules (from the digested food).
Systemic and Pulmonary circulatory system
Humans have a closed double circulatory. That means that blood passes twice the heart on one single journey. In the first step, blood circulates in the pulmonary circulation and then through the systemic circulation.
Pulmonary circulation: These are veins and arteries that go to and from the lungs. The blood is first in the right ventricle of the heart, where it will go to the pulmonary arteries (that have unlike the other arteries deoxygenated blood) and then directly to the lungs, where it branches in two ways so the blood will go to both lungs. After taking up oxygen the now oxygenated blood leaves the lungs and goes through the pulmonary veins (which are unlike other veins oxygenated) and the pulmonary circulation ends in the left atrium of the heart.
Systemic circulation: These are arteries and veins that go to and from the body. The oxygenated blood leaves the left ventricle of the heart and is pushed with a great force through the whole body. The blood will go through the aorta and then supply the whole body with oxygenated blood. After that, the blood will go through the veins and the venae cave which leads directly into the right atrium of the heart, closing the double circulatory system.