Blood : a study in general physiology / by Lawrence J. Henderson.

  • Lawrence Joseph Henderson
Date:
1928
Catalogue details

Licence: In copyright

Credit: Blood : a study in general physiology / by Lawrence J. Henderson. Source: Wellcome Collection.

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    or, in words, such that the difference between the carbon dioxide pressure at the point and the carbon dioxide pres¬ sure of the alveolar air, divided by the difference between the oxygen pressure at the point and the oxygen pressure of alveolar air is constant, are points which define a slope on the Cartesian coordinates. The meaning of this slope may be understood from the following considerations. Instead of speaking of a point on the chart as defining a given condition of the blood, we may speak of the blood as existing at a point on the chart. Then, in order to reach the arterial point, the blood may be said to describe a curve upon the chart, and the direction in which the blood must be moving when at the point p is that of the slope mP, in question. In other words, this slope is the slope of the tangent, at the point p, to the curve over which the blood must pass as a result of a diffusion process. This is true because, as already ex¬ plained, when the blood is at the point p, di/_d (total C02)^a (pCQ2)L- (pCQ2)B=:^xA(pC02) = w . dx d (total 02) a1 (p02)l—(p02)B ax A(p02) It is, accordingly, convenient to draw a family of con¬ tour lines, each one such that for every point of the con¬ tour line <h (pCQ2)L — (pCQ2)B _ <h ax (p02)L — (p02)B ax A W) — m — a constant A(p02) Here (pC02)B and (p02)B are the carbon dioxide pres¬ sure and oxygen pressure corresponding to any point, p, of the contour line and (pC02)L and (p02)L the carbon dioxide pressure and the oxygen pressure corresponding to the alveolar air point, L. Next, taking — = 20, the characteristic slope, = d1 d (total CO2) ^e£ne(j py eac]2 contour line, is calculated, d (total 02) and a large number of short parallel lines of the calcu¬ lated slope, each intersecting the contour line, are drawn.
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