The physiology of the circulation in plants : in the lower animals, and in man : being a course of lectures delivered at surgeons' hall to the president, fellows, etc of the Royal college of surgeons of Edinburgh, in the summer of 1872 . he instant the blood regurgitates. The greatvessels are thickened where the segments approach each other (, A, b), and thinned and dilated behind each segment (b, i), to formthree large cavities or sinuses, known as the sinuses of Valsalva (b, d).These sinuses contain a considerable amount of residual blood, which,by its weight and pressure, assists in
The physiology of the circulation in plants : in the lower animals, and in man : being a course of lectures delivered at surgeons' hall to the president, fellows, etc of the Royal college of surgeons of Edinburgh, in the summer of 1872 . he instant the blood regurgitates. The greatvessels are thickened where the segments approach each other (, A, b), and thinned and dilated behind each segment (b, i), to formthree large cavities or sinuses, known as the sinuses of Valsalva (b, d).These sinuses contain a considerable amount of residual blood, which,by its weight and pressure, assists in closing and wedging the seg-ments together during the diastole. They are also the receptacleswhich receive the segments during the systole—an arrangementwhich increases the diameter of the great vessels at their origins atthis particular period (Fig. 87, e). When the reflux of the bloodoccurs, the segments of the semilunar valves fold or bend at theircentral portions in such a manner that their free crescentic marginsbecome accurately applied to and flattened against each other, theflattening increasing according to the pressure. This arrangementeffectually prevents regurgitation in healthy valves (Fig. 133, a,b,c,d). Fig. Fig. 133. A, Section of pulmonary artery and right ventricle of human heart between the segments of the semilunar valve. Shows the variation in the thickness of the vessel(a,b) and how it bifurcates (?•) at its origin, s, Segment of valve, c, ft, t,f, Fibrous frameworkBun-oundingit. d, Sinus of Valsalva, e, Pulmonic fibrous ring, v, Ventricle.— Original. B.— Similar section, carried through pulmonary artery (a, 6) and middle of segment (s).Shows the thinning of the vessel in this situation (i). c, Portion of fibrous framework, d,Sinus of Valsalva, e. Pulmonic fibrous ring, v. Ventricle.—Original. C.—Human semilunar valve distended with plaster of Paris, and one of the segments (g)removed to show the shape of the lunula? or opposing surlac S
Size: 2944px × 849px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1870, booksubjectblo, booksubjectblood
