Human physiology : designed for colleges and the higher classes in schools and for general reading . into the right auricle. From this it passes into theright ventricle, which sends it by the pulmonary artery to thelungs. From the lungs it returns by the pulmonary veins tothe left auricle. It then passes into the left ventricle, fromwhich it is sent by the aorta to all parts of the body. 125. In Fig. 33 is represented the heart, situated betweenthe two lungs, with the arteries which carry blood from it, and 82 HUMAN PHYSIOLOGY. Situation and connections of the heart. Iu harmonious action. the


Human physiology : designed for colleges and the higher classes in schools and for general reading . into the right auricle. From this it passes into theright ventricle, which sends it by the pulmonary artery to thelungs. From the lungs it returns by the pulmonary veins tothe left auricle. It then passes into the left ventricle, fromwhich it is sent by the aorta to all parts of the body. 125. In Fig. 33 is represented the heart, situated betweenthe two lungs, with the arteries which carry blood from it, and 82 HUMAN PHYSIOLOGY. Situation and connections of the heart. Iu harmonious action. the veins which pour their blood into it. The lungs are repre-sented as being drawn apart to the right and left in front, soas to expose fully the heart and its vessels. The sac containingthe heart, and the packing cellular tissue are removed, so as tolay the heart and its vessels bare. At a is the trachea or wind-pipe ; on either side of it are the two arteries, the carotids,which go to the head; c is the artery which goes to the arm;b, b, are the jugular veins coming from the head, d, d, the veins. e f g h i LUNGS, HEART, AND PRINCIPAL BLOOD-VESSELS. from the arms, all empting their contents, as you see, into thedescending cava; e is the right auricle, receiving the bloodfrom the two cavse; / the ascending cava; g the right ventri-cle, i the left ventricle, and h the descending aorta. 126. I have been thus particular, and have led you throughsome repetitions in the description of some of the figures, inorder that you may get a clear idea of the complicated mecha-nism of the circulation. And now, perhaps, you will inquire,in what way all these four apartments of the heart contractand dilate, so as to have the organ act as one harmoniouswhole. You have seen how the auricle and ventricle of one THE CIKCULATION. 83 The causes of the two sounds of the heart. Its forward impulse. side act in relation to each other—the auricle contracts whenthe ventricle dilates, and the ventricle con


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Keywords: ., bookauthorhookerwo, bookcentury1800, bookdecade1850, bookyear1854