DISTURBANCES OF CIRCULATION 



Life and health are possible for the organs only if there be 

 unimpaired circulation of a blood capable of supplying oxygen 

 and nutrition to them. Disturbances of the circulation, as well as 

 faults of the blood and lymph, in other words, deficiency in the 

 provision and passage of good blood through the organs, endanger 

 both life and health. 



The normal heart possesses a notable adaptabilty to the varying 

 demands upon its capacity for work ; it accommodates itself im- 

 mediately to the current of blood entering it by virtue of the elas- 

 ticity of its walls ; regulates the energy and rhythm of its contrac- 

 tions in conformity to the amount of blood in its chambers, the 

 general circulatory resistance and the demand for blood in the ac- 

 tive or resting organs. This power of accommodation enables it, to 

 a certain extent, to overcome and compensate for pathological dis- 

 turbances affecting the hasmic circulation ; under such circumstances 

 there is said to take place a compensation for these disturbances. 



Where such conditions of resistance to the heart's action are 

 of slow development and permanent, a thickening of the myocar- 

 dium is assumed in connection with the increased requirement for 

 work, consisting essentially in an increase in the number and size 

 of the muscular elements (cardiac hypertrophy). It may be 

 said that even physiologically the size and muscular strength of the 

 heart are adjustable to the demands made upon it in its function 

 as a forcing-pump or as a suction pump. Certain animals, for 

 example, which in the course of their lives perform especially 

 intense muscular work, are likely to exhibit hearts larger in pro- 

 portion to the body-weight than animals accustomed to but little 

 muscular activity."*- Pathological hypertrophy differs from this 

 physiological form only in its cause, in the latter the excessive 

 work being but a natural and customary condition in the life of the 

 animal, in the former the result of abnormalitv of the vascular 



►See also Kitt, Lehrbuch der patliol. Anatomic d. Haustiere. II. Aufl. 



