THK HKAkl 



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but its rate varies in different individuals. It is generally- 

 quicker in women than in men. The heart beats more quickly 

 \\hen work is being done because the tissues need more blood. 

 Course of the General Circulation. The aorta, 

 leaving the ventricle and giving off the coronary arteries, first 

 forms an arch, the arch of the aorta, from which, in man, three 

 large branches are given off. The first of these, a large one 

 on the right side, immediately divides into two, one of which, 

 called the right subclavian artery, goes to the right 

 arm, while the other, called the right carotid artery, 

 goes to the right side of the neck and head. The aorta 



R.J.V 



S.C 



Fit'.. 44.--Front view of ihc heart, great vessels, and lungs. 



R>V% rigl't ventricle; L. /-", left ventricle; K.A, right auricle; LA, left auricle; 

 -/<, aurta curving backwards to the left ; /'..V, superior vena cava ; / './, 

 inferior vena cava; C, carotid arteries; R.J.V, L.J.V, right and left jugular 

 veins; S.C, subclavian vessels, artery and vein on each side; K.L, L.L, right 

 and left lungs; P. A, pulmonary artery dividing into two; /'./', pulmonary 

 veins ; /', trachea ; />', bronchi. All the vessels except those of the lungs are 

 cut. 



then gives off from the arch the left carotid artery to the left 

 side of the neck and head, and farther on the lelt subclavian 

 artery to the left arm. Continuing to arch backwards towards 

 tin- spine, the aorta runs downwards through the thorax, giving off 

 branches to the walls of the thorax and to the bronchial tubes 



