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What Is Ligature?

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“Since all things, both argument and ocular demonstration, show that the blood passes through the lungs, and heart by the force of the ventricles, and is sent for distribution to all parts of the body (V, pg. 35), where it makes its way into the veins and porosities of the flesh, and then flows by the veins from the circumference on every side to the centre (XI, pg. 60), from the lesser to the greater veins (XIII, pg. 69), and is by them finally discharged into the vena cava and right auricle of the heart (XIII, pg. 72), and this in such a quantity or in such a flux and reflux thither by the arteries, thither by the veins, as cannot possibly be supplied by the ingesta, and is much greater than can be required for mere purposes of nutrition …show more content…

59-60). Harvey uses the example of different types of ligatures when placed above the elbow, one being of complete tightness and the other being of medium tightness. When the ligature is as tight as it can possibly be, no pulse will be felt in the wrist and the arteries above the ligature will become engorged (XI, 61). With such a ligature, no blood from the arteries can enter the portion of the arm below the ligature, and therefore there is no pulse. If one applies ligature of medium tightness, however, there will be a pulse and the arm below the ligature will become discolored and distended (XI, 61-62). With a ligature of medium tightness, the blood will continue to pump from the arteries into the veins, but will be stopped by the ligature, filling the arm with more and more blood. The use of these types of ligatures prove that there is some sort of transfer of blood between the arteries and veins, either through “anastomosis” or “porosities of the flesh” (XI, 60), and resultantly, is further proof that there is a circular pattern in the motion of blood through the …show more content…

Valves were first discovered by Hieronymus Fabricius of Aquapendente, which are flaps of membrane in semilunar shape found throughout the veins (XIII, 68). Harvey goes on to explain that the valves prevent the blood from returning from whence they came, as one cannot move a probe through the vein in the opposite direction of the blood flow as it is obstructed by these valves, but can move freely in the direction blood naturally travels (XIII, 68). It is also proven that the flow of blood through the veins moves from smaller trunk to larger, as it is impossible to move the probe from the veins of larger trunks to those of smaller, for it is stopped by the valves, but the probe may move without hindrance when going the opposite direction (XIII, 70). In experiments to prove these findings, Harvey again uses a ligature and moves the blood of a vein up the arm with no obstruction, but if pushing the blood of the vein down the arm, the blood is stopped by a valve and cannot flow past the valve (XIII, 70-71). The valve acts as a floodgate, only permitted a flow of blood in the direction towards the heart. In keeping the arm bound, Harvey also uses his finger to stop the flow of blood in the distended portion of the arm, and with another finger, pushes the blood that is between the ligature and finger up the arm. It is to be

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