A System of midwifery : including the diseases of pregnancy and the puerperal state . the general venous system of thechild. As the other functions of the foetusdepend chiefly upon the modifications ofwhat Ave know as the adult apparatus, wemay here describe these shortly. The Foetal (Circulation.—The blood whichreturns from the placenta by the umbilicalvein (Fig. 7J. /) is charged with 0x3derived from the mother, so that the term•• venous blood is here, in it< ordinarysense, inapplicable. After passing throughthe umbilicus, the vessel divides. A por-tion of its contents enters the liver, a
A System of midwifery : including the diseases of pregnancy and the puerperal state . the general venous system of thechild. As the other functions of the foetusdepend chiefly upon the modifications ofwhat Ave know as the adult apparatus, wemay here describe these shortly. The Foetal (Circulation.—The blood whichreturns from the placenta by the umbilicalvein (Fig. 7J. /) is charged with 0x3derived from the mother, so that the term•• venous blood is here, in it< ordinarysense, inapplicable. After passing throughthe umbilicus, the vessel divides. A por-tion of its contents enters the liver, alongwith the blood which is being returnedfrom the intestines by tin- vena porta? 1 and, after circulating in that organ, enters the vena ca\a at h. The greater portion ofit, however, passes direct to the vena cava, by the ductus V€fh08US (</). which joins the main trunk at a point a little Lower than the hepatic vein. The blood, being thus mixed with the systemic venOUS Current, arrives at the heart much more feebly oxygenated than it was a! the umbilicus, and passing. Circulatory ipparatui in tin totai 138 DEVELOPMENT OF THE EMBRYO AXD FCETUS. [CHAP. into the right auricle, is directed by the Eustachian valve towards theforamen ovale, a special aperture through which the blood from theinferior cava is transmitted to the left auricle. From this point thecurrent passes to the left ventricle, and from thence, as in the adult, tothe aorta, almost the whole of this supply proceeding to the head andBuperior extremities by the three great vessels of the aortic arch, toreturn again to the right auricle by the superior cava. Although amixture of the two currents from the venae cavae must, to some extent,inevitably occur, the blood of the superior vein passes, almost in itsentirety, through the tricuspid valve into the right ventricle, and thenceto the commencement of the pulmonary artery. The condition of thelungs not being such as to receive this large column of blood, ano
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Keywords: ., bookcentury1800, bookdecade1870, booksubjectobstetrics, bookyear1
