. A text-book of physiology : for medical students and physicians . which it is applied, the position ofthe heart apex with reference to the chest wall, and with the con-ditions of the circulation, and it is often difficult to give it a correctinterpretation. An uncomplicated form of the cardiogram isrepresented in Fig. 229, 7, and a curve more difficult to interpret inFig. 229, 8. It should be borne in mind that the cardiograph curveis partly a pressure curve and partly a volume curve,—that is, thechanges in volume as well as the changes in pressure of the heartduring systole will affect the
. A text-book of physiology : for medical students and physicians . which it is applied, the position ofthe heart apex with reference to the chest wall, and with the con-ditions of the circulation, and it is often difficult to give it a correctinterpretation. An uncomplicated form of the cardiogram isrepresented in Fig. 229, 7, and a curve more difficult to interpret inFig. 229, 8. It should be borne in mind that the cardiograph curveis partly a pressure curve and partly a volume curve,—that is, thechanges in volume as well as the changes in pressure of the heartduring systole will affect the instrument. The Intraventricular Pressure During Systole.—The bestanalyses of the details of the systole of the ventricle have been madeby a study of the changes in pressure within the ventricle. Forthis purpose a tube filled with liquid is introduced into the cavity ofthe ventricle. A tube used for such a purpose is designated as aheart-sound. For the right ventricle it is introduced through anopening in the jugular vein and pushed down until it lies in the. Fig. 230.—Synchronous record of the intraventricular pressure (V), and the aorticpressure (A): S, The time record,—each vibration = xJs sec; 0-5, corresponding ordi-nates in the two curves; 1 marks the opening ot the semilunar valves; 3 (or shortly after)marks the closure of these valves and the beginning of diastole.—(Hiirthle.) ventricle, or in some cases it may be thrust through the wall ofthe ventricle. For the left ventricle it is introduced by way of thecarotid or subclavian artery, or through the left auricle or sound is then connected to a suitable recording apparatus byrigid tubing filled with liquid. The changes in pressure in theventricle are extensive and very rapid. To register them accu-rately the recording instrument must respond with great prompt-ness and at the same time must be free from inertia movements. 548 CIRCULATION OF BLOOD AND LYMPH. A mercury manometer, for instance, would
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