File:A manual of human physiology, including histology and microscopical anatomy, with special reference to the requirements of practical medicine (1885) (14781316975).jpg

Identifier: manualofhumanphy01land (find matches)
Title: A manual of human physiology, including histology and microscopical anatomy, with special reference to the requirements of practical medicine
Year: 1885 (1880s)
Authors: Landois, L. (Leonard), 1837-1902 Stirling, William, 1851-1932
Subjects: Physiology Histology
Publisher: Philadelphia, P. Blakiston, Son, and Company
Contributing Library: MBLWHOI Library
Digitizing Sponsor: MBLWHOI Library

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minute) the pause = 04 sec., theauricular contraction = (H77 sec. In Fig. 25«, A, the time occupied bythe pause + the auricular contraction (74 beats per minute) = 05 sec. 80 TIME OCCUPIED BY THE VENTRICULAR SYSTOLE, In D the a ft = 19 to 20 vibrations = 032 sec.; in E= 26 vibrations= 0-42 sec. Ventricular Systole.—The ventricular systole is calculated from thebeginning of the contraction, ft to e, when the semi-lunar valves areclosed; it lasts from the first to the second sound. It also variessomewhat, but is more constant. When the heart beats rapidly, it issomewhat less—during slow action, greater. In E = 0-32 sec.; in D= 029 sec.; with 55 beats per minute Landois found it = 0*34, with avery high rate of beating = 0199 sec. When the ventricle beats feebly, it contracts more slowly, as can be shown byapplying the registering apparatus to the heart of an animal just killed. In Fig.27, from the ventricle of a rabbit just killed, the slow heart-beats, B, ai-e seen tolast longest.
Text Appearing After Image:
Fig. 27. Curves obtained from the ventricle of a rabbit, and written upon a vibrating plateattached to a tuning-fork (vibration —001613 sec.)—A, tolerably) soon afterdeath ; B, from the dying ventricle. In calculating the time occupied by the ventricular systole we must remember—(1.) The time between the two sounds of the heart, i.e., from the beginning of thefirst to the end of the second sound (fc to e). (2.) The time the Hood flows into theaorta, which comes to an end at the depression between c and r? (in Fig. 25a, E).Its commencement, however, does not coincide with b, as the aortic valves openOOSS (Landois) to 0073 (Rive) sec. after the beginning of the ventricular systole.Hence the aortic current lasts OOS to 009 sec. This is calculated in the following way :—The time between the first sound ofthe heart and the pulse in the axillary artery is 0137 sec., and of this time 0052sec. are occupied in the propagation of the pulse-wave along the 30 cm. of arterylying between th

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