172 STUDIES IN ADVANCED PHYSIOLOGY. 



means that in the short period of one hour, an amount of 

 blood not far from six barrels traverses the heart. 



THE ENERGY WITH WHICH THE HEART WORKS. 



In determining the actual work done by anything it is 

 not sufficient to know the amount of matter handled, but we 

 must also know the distance through which it is lifted. 

 Thus, in pumping liquids, it requires just twice as much 

 work to pump the same amount of liquid twice as high. 

 The energy with which the ventricles force out their con- 

 tained blood is not difficult to calculate. Repeatedly veri- 

 fied experiments show that the left ventricle sends its blood 

 out with such force, that if there were no friction it would 

 be thrown vertically upwards about a distance N of nine feet. 

 The force with which the right ventricle throws out the 

 same amount of blood is one-third as much, being in this 

 case a distance of only three feet. Or, to explain this still 

 further, it means that the left ventricle forces the blood out 

 with an energy that would cause the blood to rise nine feet 

 high in a tube, barring friction. Or, to re-state it again, it 

 means that if there were no friction in the arteries the heart 

 would force blood, say, up to the finger tips if the arms 

 should be held vertically upwards, even though the distance 

 from the finger tips to the heart were nine feet. 



, Now, work is the product of the amount of matter 

 lifted, and the distance through which it is lifted. A unit 

 of work is a foot-pound. A foot-pound is the amount of 

 work required to lift one pound one foot high. Knowing 

 the amount of blood which each ventricle throws out and 

 the height to which it would be thrown if unhindered, it is 

 easy to determine the amount of work the heart is enabled 

 to do in definite periods of time. Thus, at every beat the 

 left ventricle throws out 100 grams, or about 3-nr ounces, 

 or about .22 pound, taking approximate figures only. The 

 amount of work is expressed by the product of the numbers 

 giving the amount and height. Thus the work of the left 

 ventricle for one beat would be 9X.22; that is, 1.98 foot- 



