Control of human placental blood flow.
An overall scheme is proposed for the control of blood flows in both fetal and maternal circulations of the human placenta. The first part of the hypothesis is that fetoplacental vascular resistance is controlled locally by a reversible hypoxic fetoplacental vasoconstriction (HFPV) in response to reduced local maternoplacental oxygen delivery. Also suggested is humoral limitation of the extent of HFPV by substances circulating in hypoxic fetal blood. Secondly, it is hypothesized that maternoplacental vascular resistance is controlled humorally by release of hormones into maternal blood from the fetoplacental unit. Finally, it is proposed that chronic local maternoplacental ischemia associated with placental "aging" can induce an irreversible fetoplacental vasoconstriction by a mechanism different from HFPV in order to permanently shut down fetal blood flow to the area(s) affected.
D005260:Female; D005865:Gestational Age; D006801:Humans; D000860:Hypoxia / Q000503:physiopathology; D008431:Maternal-Fetal Exchange; D008954:Models, Biological; D010920:Placenta / Q000098:blood supply*; D011247:Pregnancy; D012039:Regional Blood Flow; D014655:Vascular Resistance; D014661:Vasoconstriction