CIRCULATION OF THE BLOOD. 



529 



Fig. 220.— Blood-Pkessure Curve, drawn by Mercurial Manometer. ( Yeo.) 



O to x = zero line, y to yf = curve with large respiratory waves and small waves of heart impulse. A scale 

 is introduced to show height of pressure in millimeters of mercury. 



Fig. 221.— Diagram showing the Relative Heights of Blood Pressure 

 in the Different Regions of the Vessels. (Yeo.) 



H, heart; A, arteries; a, arterioles ; r, capillaries; V, small veins; v, large veins; H V, being the 

 zero line, the pressure is indicated by the elevation of the curve. The numbers to the left give the 

 pressures (approximately) in millimeters of mercury. 



34 



