A manual of obstetrics . ntois. The method bywhich the oxygenation of the blood is accomplished priorto this time remains undetermined. Respiration in thefetus after the formation of the placenta is piscine in nature,the gaseous interchange being accomplished through themedium of a fluid, the maternal blood. The fetal blood,contaminated by an absorption of carbonic-acid gas duringits passage through the fetal structures, finally reaches thechorion, where it is exposed, over the widely-extended sur-face afforded by the chorionic villi, to the revivifying actionof the maternal blood. The carboni
A manual of obstetrics . ntois. The method bywhich the oxygenation of the blood is accomplished priorto this time remains undetermined. Respiration in thefetus after the formation of the placenta is piscine in nature,the gaseous interchange being accomplished through themedium of a fluid, the maternal blood. The fetal blood,contaminated by an absorption of carbonic-acid gas duringits passage through the fetal structures, finally reaches thechorion, where it is exposed, over the widely-extended sur-face afforded by the chorionic villi, to the revivifying actionof the maternal blood. The carbonic dioxid is abstracted,its place is supplied by fresh oxygen from the maternalblood, and the bright-red blood thus produced, enriched bythe further absorption of the nutritious pabulum, re-entersthe fetal circulation. 62 A MANUAL OF OBSTETRICS. Fetal Circulation (Fig. 32). — In order that the pabu-lum and oxygen supplied at the placental site shall gain L Com CuYOUcL R Suhtlo SuJiei-ioT Vena Cavot - -J-~-r. UmbiUcu Placenta, KiG. 32.—Diagrammatic view of the fetal circulation. access to the various fetal tissues, it becomes necessary thatthey be distributed throughout the body through the agencyof the vascular system. Owing to the non-activity of the THE PHYSIOLOGY OF PREGNANCY. 63 respiratory and digestive systems there is evolved a com-plex method of circulation, varying very radically from thatwhich takes place in the individual ex utcro. The centerfrom which the blood is derived, and to which it is impelledby the action of the fetal heart, is the placenta; here it isthat the impure venous blood is depleted and the rich redarterial blood is elaborated, and hence it is here that a sys-tematic study of the fetal circulation should begin. Surcharged with its vital constituents, the blood collectsfrom the venous radicles in the chorionic villi and finds itsway into the large umbilical vein. This passes down theumbilical cord to the navel, and thence is carried t
Size: 1257px × 1988px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1890, booksubjectobstetrics, bookyear1
