The encyclopædia britannica; a dictionary of arts, sciences, literature and general information . dby eddies setting some part of the membranous walls or valve flaps invibration. If a stethoscope be placed over a large artery, a murmur will be VASCULAR SYSTEM 935 heard caused by the blood rushing through the vessel narrowed by?he pressure of the instrument. The flmd e«:apcs into a wder tne pressurt oi i portion of the vessel beyond the point of pressure, and thesound is caused by the eddiesset up there throwing themembranous wall of the vesselinto vibration. Such a sound isheard over an aneuri
The encyclopædia britannica; a dictionary of arts, sciences, literature and general information . dby eddies setting some part of the membranous walls or valve flaps invibration. If a stethoscope be placed over a large artery, a murmur will be VASCULAR SYSTEM 935 heard caused by the blood rushing through the vessel narrowed by?he pressure of the instrument. The flmd e«:apcs into a wder tne pressurt oi i portion of the vessel beyond the point of pressure, and thesound is caused by the eddiesset up there throwing themembranous wall of the vesselinto vibration. Such a sound isheard over an aneurism. Theplacental bruit heard duringpregnancy is a sound of thiskind, arising from pressure onthe uterine arteries. In cases/ of insufficient aortic valves a/ double blowing murmur maybe heard, the first being due tothe rush of blood into thevessel, and the second to theregurgitation of the blood backinto the ventricle. These niur- „ ,. ^ 1 murs are produced by eddies Fig. 14.—SchemeofaC-ardiacl-ycle. ^f blood setting the mem-The mner circle shows what events i,ranous parts into vibration. through the coronary arteries of a dog to mamtain the vigour of the heart. , . , • ^ ? u- i. r *i. The use of oxygen per grra. of weight per minute is high tor theheart. Thus for the whole body of the dog there was used?017 CO. per grm. per min., for the heart •045--oS3, j.^^and for the active secretory glands -oy-l-o Cgarcroit^rtiVicMand Dixon). It has long been known that the heart ol ^,.„„, or tortoise can be kept beating normally for hours (,„„ „,after removal from the body, if it is provided with ,1,^ ijg^ruan artificial circulation of blood or a suitable solution ofsalts. Sydney Ringer worked out the necessary ingredients 01 tnissolution to be Sodium chloridePotassium „Calcium 0-7%0-03 %0-025% The inner circle show, . ^ occur in the heart, and the outer Occasionally a murmur isthe relation of the sounds and produced by the displacementsilences to these events.
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectencyclo, bookyear1910
