. Elements of human physiology. Physiology. THE VASCULAR MECHANISM 217 (Fig. 115). In the dog the maximum pressure in the left ventricle may be 140 mm., in the right ventricle 60 mm., and in the right auricle about 20 mm. Hg. The use of the mini- mum manometer reveals the striking fact that, at some period of the cardiac cycle, there is a negative pressure in the ventricle; that is to say, the mercury is sucked up in the limbs of the manometer towards the heart. This negative pressure may amount to 30 or 40 mm. Hg. in the left ventricle, to 15 mm. in the right ventricle, and to 7 or 8 in the r
. Elements of human physiology. Physiology. THE VASCULAR MECHANISM 217 (Fig. 115). In the dog the maximum pressure in the left ventricle may be 140 mm., in the right ventricle 60 mm., and in the right auricle about 20 mm. Hg. The use of the mini- mum manometer reveals the striking fact that, at some period of the cardiac cycle, there is a negative pressure in the ventricle; that is to say, the mercury is sucked up in the limbs of the manometer towards the heart. This negative pressure may amount to 30 or 40 mm. Hg. in the left ventricle, to 15 mm. in the right ventricle, and to 7 or 8 in the right auricle. If however we register the variations of endocardiac pres- sure by means of a manometer which is sufficiently accurate Fig. 115. to manometer max. valve. mm. valve to heart . Frank's valve. This is placed in the course of the tube between heart and manometer, so that the latter may be used as a maximum, minimum, or ordinary manometer according;- to the tap which is left open. to record the quick changes in pressure that occur in the ventricle with each heart-beat, we get a curve like Fig. 116. By registering this curve simultaneously with that of the blood-pressure in the aorta, we may determine what events are occurring during each phase of the curve. The auricular systole in some tracings causes a small rise of endocardiac pressure, represented by an elevation on the curve which would occur before the ordinate 0. It generally lasts about 0*05 second. It is not represented in the curve reproduced in Fig. 116. This is immediately followed by the ventricular. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Starling, Ernest Henry, 1866-1927. Chicago : W. T. Keener
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