A textbook of human physiology / translated from [the] 6th German edition by W. Stirling.

  • Landois, Leonard
Date:
1888
Catalogue details

Licence: Public Domain Mark

Credit: A textbook of human physiology / translated from [the] 6th German edition by W. Stirling. Source: Wellcome Collection.

Provider: This material has been provided by Royal College of Physicians, London. The original may be consulted at Royal College of Physicians, London.

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    greater blood-pressure there. Complete diastolic relaxation of the ventricle occurs from e to / in the curve. It is clear, then, that the cardiac impulse is caused chiefly by the contraction of the ventricles,, while the auricular systole and the vibration caused by the closure of the semi-lunar valves are also concerned in its production. [Change in Shape of Heart.—The experiments of Ludwig and Hesse on the heart of the dog show that the shape of the ventricles varies remarkably in systole and diastole, and that the shape of the heart as found post-mortem is not its natural shape.] [Method.—Bleed a dog raj^iidly froni the carotids, detibiiiiate the blood, expose tlie heart, tie graduated straight tubes into the puhuonary artery and aorta, and ligature the auricular vessels. Pour the blood into the heart until it is dilated under a pressure equal to the mean arterial pres- sure (150 mm.). The ventricles are in the diastolic piiase, the auricles still pulsate. A plaster cast is now rapidly made of the ventricles. This represents the diastolic phase. To obtain what may be regarded as the systolic phase, a heart, similarly prepared but em.ptied of blood, is suddenly plunged into a hot (50° C.) saturated solution of potassic bichromate, when the heart gives one rapid and final contraction and remains permanently contracted owing to the heat- rigor, its proteids being coagulated (§ 295). This is the systolic phase. Little pins with twisted points are previously inserted in the organ to mark certain parts of both hearts for comparison.] [In diastole, the shape of the ventricle is hemispheroidal, the apex being rounded, while the posterior surface is flatter than the anterior (tig. 41). In the plane of the ventricular base, the greatest diameter is fi-om right to left, and the shortest from base to apex. The conus arteriosus is above the plane of the base. During Fi''. 41. Projection of a dog's heart. Posterior surface. Fig. 42. Anterior surface. Fig. 43. Left lateral surface. systole, the apex is more pointed, the ventricle more conical, while all the diameters in the plane of the base are equally diminished, hence the vertical measurement from base to apex is longer now than either of the diameters at the base (fig. 43). The conus arteriosus sinks towards the plane of the base, while the base of the ventricle becomes more circular, so that the difference of the curvatures of the anterior and posterior surfaces van- ishes (fig. 42). In all these figs, the shaded part represents diastole and the clear part systole. The most re- markable point is that the vertical measurement remains unchanged. This refers to the left ventricle, which of course forms the apex; the right is shortened. The plane of the ven- tricular base in systole is about one- Fig. 44. FiL'. 45. half of what it is in diastole, as is Projection of the base in A, aorta ; PA, pulmon- shown in fig. 44. Thus the heart is svstole and diastole, RV, ary artery; M, mitral, diminished in all its diameters except '^ xi 4. • 1 -c 1 tricle. nee. one, the arterial orifices are scarcely affected, while the area of the auriculo-ventricular orifices (M, T) is diminished about one-half (fig. 45). This is most important in connection with the closure of E
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