no THE ENGINES OF THE HUMAN BODY 



universal piston. The entire wall moving inwards, thus 

 drives the blood from the left ventricle through the 

 outlet valve into the aorta. The engine which works 

 the ventricular pump is not set up some distance away, 

 but is actually built into its walls. The thickness of the 



Pump 



AIR CHAMBER 



(ei 'as tic) 



ELASTIC CHAMBER 



RESER VOIR 



(Auricle) 



Fig. 29. — The various parts of a force-pump (A) compared with the parts 

 of the left ventricular pump (B). 



wall of the left ventricle represents a muscular engine, 

 one made up of countless microscopic cylinders of a 

 rather peculiar kind, differing somewhat from the 

 cylinders of body muscles. The total weight of the 

 muscular engine which expels the contents of the left 

 ventricle is just under a quarter of a pound in a person 

 whose body- weight is no lb. These figures are based 



