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

  • Landois, Leonard
Date:
1888
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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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    analvses it is difficult to do this, and the best plan to pursue in that case is to keep the recep- tacles containing the blood on ice. _ Mavo\v (1670) observed that gases were given off from blood in vamo. Magnus (183/) in- vestit'ated tlie percentage composition of the blood gases. The more important recent investi- gations have been made by Lothar Mej'er (1857), and by the pupils of 0. Ludwig and E. Pfliiger. 35. QUANTITATIVE ESTIMATION OF THE BLOOD GASES.—The gases obtained from blood consist of 0, C0._,, and N. Pfliiger obtained (at 0° C. and 1 metre Hg pressure) 47S volumes per cent., consisting of— 0, 16-9 per cent. ; CO^, 29 per cent.; N, 14 per cent. As is shown in fig. 22, J, the gases are obtained in an eudiometer, i.e., in a narrow tube, closed at one end, and with a very exact scale marked on it, and having two fine platinum wires melted into its upper end, with their free ends projecting into the tube (^j and n). (1) Estimation of the CO^.—A small ball of fused caustic potash, fixed on a platinum wire, is introduced into the mixture of gases through the lower end of the eudiometer under cover of the mercury. The surface of the potash ball is moistened before it is introduced. The CO^ unites with the potash to form potassium carbonate. The potash bulb is withdrawn after 24 hours. The diminution in volume indicates the amount of CO^ absorbed. (2) Estimation of the 0.—(a) Just as in estimating the CO.,, a ball of phosphorus on a platinum wire is introduced into the eudiometer ; it absorbs the 0 and forms phosplioric acid. Another plan is to employ a sTnall papier-mache bull saturated with pyrogrtUic oxid iti cattstic jwtash, which rapidly absorbs 0. After the ball is removed, the diminution in volume indicates the quantity of 0. (h) The 0 is most easily and accurately estimated by cx2)loding it in the eudiometer. Intro- duce a sufficient quantity of H into the eudiometer, and accurately ascertain its volume ; an electrical spark is now passed between the wires, p and n, through the mixture of gases ; the 0 and H unite to form Avater, Avhich causes a diminution in the volume of the gases in the eutlio- meter, of which ^ is due to the 0 used to form water (HoO). (c) Estimation of the N.—When the COo and 0 are estimated by the above method, the remainder is pure K. 36. THE BLOOD GASES.—[In human blood the average total gases are estimated to be, at 0 C. and 1 metre pressure, N 1 to 2 per cent. 1 to 2 1*4 per cent. 1-4 „ ] I. Oxygen exists in arterial blood (dog) on an average to the extent of 17 volumes per cent, (at 0° C. and 1 metre Hg pressure) {Pfliiger). According to Pfliiger, arterial blood (dog) is saturated to with O, while, according to Hiif°ner, it is saturated to the extent of i4. In venous blood the quantity varies very greatly ; in the blood of a passive muscle 6 volumes per cent, have been found ; while in the blood after asphyxia it is absent, or occurs only in traces. It is certainly more abundant in the comparatively red blood of active glands (salivary glands, kidney), than in ordinary dark venous blood. [Modifying Conditions.—The amount of 0 obtainable from the blood depends upon the organ from which the blood comes, or whether the organ be active or at rest. Thus the 0. present in the ^ Carotid artery is . . 21 per cent. I Renal vein (kidney active), Vl per cent Renal artery, . . 19 „ | Renal vein (kidney at rest), 6 Bert finds that increase of the atmospheric pressure from 1 to 10 atmosijlieres raises the amount of 0 in arterial blood from 20 to over 24 per cent., and the N from 1-8 to over 9 per cent., while the CO^ is but slightly afl'ected.] The 0 in Blood occurs—(or) sw?ip/y absorbed in the plasma. This is only a 0 CO, Arterial blood. 17 30' Venous blood, 6 to 10 .35 or, calculated at 0° C. and 760 mm. pressure. Arterial blood. 20 39 Venous blood, 8 to 12 46
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