HEART 



2746 



HEART 



for a drop of blood to make the entire round 

 of the circulation. An interesting feature of 

 this process is the fact that the two sides of 

 the heart, though doing different work, con- 

 tract and empty themselves and relax and fill 



AT LEFT 



The left auricle and ventricle opened. A part 

 of the left and anterior walls has been removed. 



(a) The two right pulmonary veins cut short; 

 their openings are seen within the auricle. 



(b) The cavity of the left auricle. The larger 

 cavity, below and to the left, is the ventricle. 



(c) The cut surface of the walls of the ventricle 

 seem to become very much thinner toward the 



(d) A small part of the anterior wall of the 

 left ventricle which has been preserved. 



(e) The mitral valve, which prevents the re- 

 turn of the blood from the ventricle to the auricle. 



(f) Showing the interior of the aorta, near its 

 commencement and above the three segments of 

 its semilunar valve, which are hanging loosely 

 together. 



(<7) The exterior of the great artery or aorta. 



(h) The root of the pulmonary artery and its 

 semilunar valves. 



(i) The arteries rising from the summit of the 

 aortic arch. 



AT RIGHT 



The right auricle and ventricle opened. A part 

 of their right and anterior walls has been re- 

 moved. 



(a) Superior vena cava. 



( b ) In f er ior vena cava. 



(c) Hepatic veins cut short. 



(d) Right auricle. 



(e) Cavity of the right ventricle. 

 (/) Tricuspid valve. 



(0) Showing the interior of the pulmonary ar- 

 tery, a part of the anterior wall of that vessel 

 having been removed, and a narrow portion of it 

 preserved at its commencement, where the semi- 

 lunar valves are attached. 



(h) The ascending part or sinus of the arch of 

 the aorta. 



(1) The outside of the left ventricle. 



at the same time. Therefore only one beat can 

 be felt. With each stroke there is a wave of 

 swelling in the walls of the arteries throughout 

 the body, which can be felt as a distinct beat 

 or throbbing in places where the artery lies 

 near the surface. 



Sounds of the Heart. Two different sounds 

 are made by the heart as ic carries on its 

 labors. The first, supposed to be caused by 

 the vibration of the contracting muscles, is a 



dull, muffled sound which can be imitated by 

 pronouncing the syllable lub ; this is followed 

 by a shorter and sharper sound dup which 

 is due to the sudden closing of the semilunar 

 valves. The first sound continues during three- 

 tenths of the beat, and is followed by a pause 

 lasting one-tenth; two-tenths are next taken 

 up with the second sound, and then there is a 

 pause lasting four-tenths of the beat. If you 

 place your ear against the chest of a person, 

 over the region of the heart, you can hear 

 these sounds distinctly. When the valves are 

 diseased and do not work properly the condi- 

 tion is indicated by a sort of blowing sound. 

 That is why the physician listens to the sounds 

 of the heart when he suspects that these valves 

 are out of order. 



Care of the Heart. If this active pumping 

 organ did not possess strong powers of endur- 

 ance it could never endure the strain to which 

 it is constantly subjected. The heart works for 

 all the other parts of the body; the stomach 

 calls for a larger supply of blood to help it 

 in digesting the food; the brain cells need 

 more blood when we are studying or thinking 

 hard; when we engage in active forms of work 

 or exercise the heart must beat faster to pro- 

 vide us with the necessary energy. Further- 

 more, its nerve cells are very sensitive and 

 respond quickly to outside influences. A sud- 

 den, unexpected outcry, for instance, makes 

 it beat faster; its action is hastened by anger, 

 joy, excitement, etc. Thus it is seen that 

 there are numerous demands made upon the 

 heart every day; for this reason we should 

 not overdo in our work or in our play. Out- 

 door exercise, if it is kept within the proper 

 limits, is excellent for building up the physical 

 organism and for strengthening the heart, but 

 overindulgence in athletic sports may bring 

 on permanent weakness of that life-sustaining 

 organ. It is a good rule to stop active exer- 

 cise when you begin to feel tired or when the 

 heart begins to beat too violently. 



All kinds of alcoholic liquors have a harmful 

 effect on the heart. Long-continued use of 

 these beverages may cause a deposit of fatty 

 tissue in place of muscular fibers, a condition 

 known as "fatty degeneration." This inter- 

 feres with the work of the ventricles and valves 

 and may cause death by heart failure. Alcohol 

 is a direct poison to the cells of the heart; it 

 overstimulates that organ and causes it to beat 

 with needless vigor, and it weakens it by im- 

 pairing the nutritive qualities of the blood 

 which nourishes it. In many states and 



