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Let us assume further how much less the heart will hold in the contracted than in the dilated state; and how much blood it will project into the aorta upon each contraction; and all the world allows that with the systole something is always projected, a necessary consequence demonstrated in the third chapter, and obvious from the structure of the valves; and let us suppose as approaching the truth that the fourth, or fifth, or sixth, or even but the eighth part of its charge is thrown into the artery at each contraction; this would give either half an ounce, or three drachms, or one drachm of blood as propelled by the heart at each pulse into the aorta; which quantity, by reason of the valves at the root of the vessel, can by no means return into the ventricle.
Atheromatous degeneration is most common in the large arterial trunks, and the changes are most marked at the arch of the aorta, opposite the flexures of joints, at the mouths of large branches, and at parts where the vessel lies in contact with bone. The presence of diseased patches in the wall of an artery diminishes its elasticity and favours aneurysmal dilatation.
All the cavities of the heart are lined with a smooth, delicate membrane, called the endocardium. Semilunar valves. 2. Tricuspid valve. 3. Mitral valve. 4. Right auricle. 5. Left auricle. 6. Right ventricle. 7. Left ventricle. 8. Chordæ tendineæ. 9. Inferior vena cava. 10. Superior vena cava. 11. Pulmonary artery. 12. Aorta. 13. Pulmonary veins.
As it descends, the aorta sends off on its passage a great number of arteries which carry the blood into all parts of the body. Arrived at the loins it forms a fork; dividing into two great branches, which continue their descent, one on each side the body, down to the very extremities of the two feet. As you perceive, dear child, this is not very difficult to remember.
Many heart patients are overdrugged. This sort of treatment is contraindicated in some kinds of heart disease, as heart weakness due to arteriosclerosis with high blood pressure, to aneurysm of the thoracic or abdominal aorta, and to nephritis.
This may not be due to narrowing of the aortic orifice; it may be due to a sclerosis of the aorta. On the other hand, it may be due entirely to the hastened blood stream from the nervous excitability. This is probably the case if this sound disappears when the patient reclines. If it increases when the heart becomes slower and the patient is lying down, the cause is probably organic. Jour.
This rapid descent greatly amused us, and we were only stopped by the mud which succeeded the snow at the distance of five or six hundred toises down the declivity. We crossed, or rather climbed up, Mont Albaredo to avoid passing under the fort of Bard, which closes the valley of Aorta.
"It was a great tax on his failing strength to make this journey; but he was ever ready to promote the welfare of the Utes, who regarded him in the light of a father. "I saw him in April, 1868. His disease, aneurism of the aorta, had progressed rapidly; and the tumor pressing on the pneumo-gastric nerves and trachea, caused frequent spasms of the bronchial tubes which were exceedingly distressing.
The necropsy revealed a penetration of the aorta through the thoracic portion of the esophagus. There is also in the Musee Dupuytren a preparation described by Bousquet, in which the aorta and the esophagus were perforated by a very irregular piece of bone. Mackenzie mentions an instance of death from perforation of the aorta by a fish-bone.
From this avowal, a little painful, I confess, my young readers may learn the inconvenience of rashly condemning others! As I said in the concluding passage, which truth, only too late, now compels me to suppress "The truth is sure to come out at last." Do you remember of my talking of the vertebral column when I was describing that great artery, the aorta, to which it forms a rampart of defence?
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