In the human placenta, fetal blood circulates in the blood vessels of the villous tree while maternal one circulates in the intervillous space, the surroundings of the villous tree. Previously, the computational model of the villous tree, whose stem villi actively contract because of the contractile cells, has been developed. The result of the computation indicated that the displacement caused by the contraction would be helpful for the fetal and maternal circulations and can be combined with the other measurements for blood circulations in the placenta. Hypoxia in the placenta is classified into the following categories: preplacental hypoxia, uteroplacental hypoxia, and postplacental hypoxia. The number and the form of the terminal villi are altered by hypoxia. Assuming that increase in the terminal villi causes a higher shear elastic modulus of the placenta, this villous tree model is useful to estimate the influence of hypoxia on the blood circulations. In this chapter, how these three types of hypoxia influence the blood circulation in the placenta by the aforementioned computational model are discussed. While preplacental hypoxia and uteroplacental hypoxia would cause similar displacement in large regions, postplacental hypoxia would do vice versa. All the types might make the fetal and maternal blood circulations difficult.
Part of the book: Highlights on Hemodynamics
Halocynthia roretzi, belonging to class Ascidiacea, has highly pure and crystalline cellulose Iβ, and sulfated chitin in its tunic. Cells, including hemocytes in the open circulatory system, are scattered in the tunic. The tunic, which maintains its thickness by continuous proliferation and removal, can be classified into active tissues. Recently, it has been reported that various stimuli, such as mechanical stimuli and changes in the mechanical environment, could cause active deformations of the tunic without changes in the characteristics of the tissue structure, which would be associated with influx and efflux of water. In this chapter, the system associated with active deformation, tissue structure and flux of water in the tunic is shown, with reference to the previous reports.
Part of the book: Plant Stress Physiology