Exercises in practical physiology (1897) (14578206998)

Identifier: exercisesinpract00wall (find matches)
Title: Exercises in practical physiology
Year: 1897 (1890s)
Authors: Waller, Augustus Désiré, 1856-1922
Subjects: Physiology Biochemistry
Publisher: London New York, N.Y. Bombay : Longmans, Green, and Co.
Contributing Library: Columbia University Libraries
Digitizing Sponsor: Open Knowledge Commons



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e it (a) filled withair or (6) filled with water, effecting perfect closure by inflatinga double india-rubber armlet fitting between the tube andthe arm. In the fiirst case you will connect the plethysmograph by atube with an ordinary Marey tympanum, or preferably with apiston-recorder, and take a record of the variations of volumecoinciding with the arterial pulse. In the second case you will connect it with a large vessel ofwater carrying a float, that rises and falls as the arm swellsand shrinks ; the float raises and lets down a lever that marksagainst a slowly revolving smoked cylinder. In this way youmay take a prolonged observation of the slow variations ofvolume of the forearm. The position of the several parts of the apparatus is suffi-ciently indicated by the figure ; movements of the limb mustas far as possible, be avoided ; and with the apparatus filled 18 EXERCISES AND EXPERIMENTS with water, the two parts should be at the same level to avoidpressure of fluid on the limb.
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Fig. 6.—Mossos Plethysmograph. Test the effects upon the volume of the limb— (1) Of Miillers experiment (strong effort of inspiration withclosed air passages). (2) Of Valsalvas experiment (strong effort of expirationwith closed air passages.) (3) Muscular contractions of the forearm. To take this last observation in a regular and knownmanner, an ordinary clinical dynamometer (with the indexarranged so that it works to and fro) is pressed at regularintervals to a regular amount—say at two-second intervals fora period of two minutes to a pressure of 22 lbs. (10 kg.). Thelimb shrinks during the contraction and then undergoes a dila-tation from which it slowly subsides. IN CHEMICAL AND PHYSICAL PHYSIOLOGY. 19 VI. — Measurement of Blood-Pressure. The Manometer (Dem.)—In preparing this demonstration it will be convenient toclear the vago-sympathetic and pass a loose ligature round, in orderto subsequently show the effect upon the blood-pressure (a) of sec-tion, (b) of excitation o