DISEASES OF THE HEART AND BLOOD-VESSELS. 



By W. H. HARBAUGH, V. S., Richmond, Va. 



Iii order to comprehend what is meant by disease, it is essential that 

 one should understand the structure and arrangement of the organs 

 subject to disease, as well as know something of the phenomena or 

 functions of the organs in a state of health, because it must be remem- 

 bered that disease is but a perversion of health. The blood and circu- 

 latory apparatus are not only of the greatest importance in the diseases 

 under this particular head, but they are more or less concerned whenever 

 disease exists. To convey an idea of their importance it may be stated 

 that all vitality and all nutrition depend on the blood. In view of 

 these facts it must be admitted that nothing less than a liberal descrip- 

 tion of these organs and their functions will suffice in a work of this 

 kind (the principal object of which is instruction), and therefore we 

 will at once proceed to an anatomical and physiological consideration 

 of them. 



The heart, blood-vessels, and lymphatics are usually described as 

 the circulatory apparatus. 



The heart is located in the thoracic cavity (chest). It is conical in 

 form, with the base or large part uppermost, while the apex or point 

 rests just above the sternum (breastbone). It is suspended from the 

 vertebral column (backbone) by the large blood-vessels which enter 

 and leave the heart. It is situated between the right and left lung, 

 the apex inclining to the left, and owing to this circumstance the 

 heartbeats are best felt on the left side of the chest behind the elbow. 

 The heart is composed principally of muscular tissue. It may be con- 

 sidered as a hollow muscle, containing four compartments, two on each 

 side. The compartments of each side are placed one above the other. 

 For convenience, the compartments are called" right and left, but in 

 reality those called right arc almost in front of those called the lot'T. 

 The upper compartments are called auricles and the lower ones are ealled 

 ventricles. The right auricle and ventricle are completely separated 

 from the left auricle and ventricle by a thiek septum or wall, so that 

 there is no communication between the right and left sides of the heart. 

 Externally the heart appears to be single, but it is really a double organ. 



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