. The clinical study of blood-pressure : a guide to the use of the sphygmomanometer in medical, surgical, and obstetrical practice, with a summary of the experimental and clinical facts relating to the blood-pressure in health and in disease . of Liquid throi^h Tubes.—Since hquids arealmost incompressible, it is clear that an intermittent flowthrough rigid tubes must always be the same at all points, andexactly the same amount must leave the tube as enters distensible tubes of elastic material, such as the arterialwalls, the conditions are different. If the tube be short andthe calibre
. The clinical study of blood-pressure : a guide to the use of the sphygmomanometer in medical, surgical, and obstetrical practice, with a summary of the experimental and clinical facts relating to the blood-pressure in health and in disease . of Liquid throi^h Tubes.—Since hquids arealmost incompressible, it is clear that an intermittent flowthrough rigid tubes must always be the same at all points, andexactly the same amount must leave the tube as enters distensible tubes of elastic material, such as the arterialwalls, the conditions are different. If the tube be short andthe calibre large in proportion to the size of the pump used, thewalls may not be put appreciably on the stretch and an inter-mittent flow will occur, much as in a rigid tube. If, however,a larger tube be used and the open end narrowed to create a 10 BLOOD-PRESSURE IN THE NORMAL ANIMAL resistance to the outflow, with the first injections httle fluidwiU leave the tube, the bulk accumulating within and distend-ing it. This, of course, raises the pressure, which in turn in-creases the outflow, so that, as the experiment continues, theflow gradually increases until a steady stream is delivered,which just equals the amount pumped in during the same. Fig. 2.—Diaseam illhstbating the flow of liquid thkough tubbs. time. When this point is reached the system is in equiUbrium,and the amount of distention of the tube and the pressure willbear an exact relation to the volume of intake and the size ofthe outlet. Such an experiment is shown in Fig. 2. If we connect amanometer (A) with the end of the tube we can measure theTotal or End Pressure at that point. If, at some otherpoint, a T-canula (B) be introduced without obstructing theflow and a manometer (C) connected with it, a pressure willbe registered slightly lower than the end pressure. This is theLateral Pressure, and is the force exerted on the wallsof the tube at that point. The difference between it and theend pressure is due to the fact t
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectbloodpr, bookyear1904
