Flow
The blood flow through the umbilical cord is approximately 35 mL/min at 20 weeks, and 240 mL/min at 40 weeks of gestation. Adapted to the weight of the fetus, this corresponds to 115 mL/min/kg at 20 weeks and 64 mL/min/kg at 40 weeks. It corresponds to 17% of the combined cardiac output of the fetus at 10 weeks, and 33% at 20 weeks of gestation.
Endothelin and prostanoids cause vasoconstriction in placental arteries, while nitric oxide causes vasodilation. On the other hand, there is no neural vascular regulation, and catecholamines have only little effect.
Read more about this topic: Fetal Circulation
Famous quotes containing the word flow:
“No care, no stop; so senseless of expense
That he will neither know how to maintain it
Nor cease his flow of riot, takes no account
How things go from him, nor resumes no care
Of what is to continue.”
—William Shakespeare (1564–1616)
“Water doesn’t flow if it’s level, and people won’t complain if you treat them on the level.”
—Chinese proverb.
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—D.H. (David Herbert)