Physiology and biochemistry in modern medicine . the heart may be made by pushing long cannula; down the large veins orarteries, or in the case of the ventricles by inserting a cannula with a sharp point directly throughthe wall of the ventricle. THE ACTION OF THE HEART L49 therefore shul off from the ventricle. The exact momenl in diastole atwhich the two cavities arc again brought into communication—, theventricular valves open—is indicated by the curves coming together. Having thus determined the exact moments of opening and closingof the auriculoventricular valve, we may now proceed to
Physiology and biochemistry in modern medicine . the heart may be made by pushing long cannula; down the large veins orarteries, or in the case of the ventricles by inserting a cannula with a sharp point directly throughthe wall of the ventricle. THE ACTION OF THE HEART L49 therefore shul off from the ventricle. The exact momenl in diastole atwhich the two cavities arc again brought into communication—, theventricular valves open—is indicated by the curves coming together. Having thus determined the exact moments of opening and closingof the auriculoventricular valve, we may now proceed to compare theintraventricular pressure curve with that taken from the aorta. After thenecessary calibration corrections, this curve has been placed in Fig. 3-4in its true relationship to the ventricular curve. Beginning again at theend of diastole, we find that the aortic pressure is very considerablyabove that of the ventricles, indicating that the semilunar valves mustbe closed; and it will be observed that the intraventricular pressure at. Fig. 34.—Pressure curves after being graduated have been superimposed. The presphygmic,sphygmic and postsphygmic periods of ventricular systole are shown by the vertical lines. TheA-V valves close at the first line. The aortic valves open at the second line and close again atthe third line. The A-V valves open at the fourth line. The position of the two main heartsounds is also indicated. the beginning of systole does not rise sufficiently to open them until anappreciable interval ( to second) after the closure of the auric-uloventricular valves; that is to say, there is a period at the beginningof ventricular systole during which the ventricle is a closed cavity. Itis a period during which the ventricle by its contraction is getting up asufficient amount of pressure in the fluid contained in it to force openthe semilunar valves against the resistance of the pressure in the aorta,and it has been popularly called the period of
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