Q. The umbilical cord links fetus and placenta. It is composed of
Solution:
Implantation is followed by the appearance of finger-like projections on the trophoblast called chorionic villi which are surrounded by the tissue and maternal blood. Interdigitation of the chorionic villi and uterine tissue with each other leads to the formation of a structural and functional unit called the placenta between the developing embryo (foetus) and maternal body.
The placenta supplies oxygen supply and nutrients to the embryo and also facilitates the removal of carbon dioxide and excretory/waste materials produced by the embryo.
The umbilical cord connects the placenta to the embryo which helps in the transport of substances to and fro from the embryo.
The umbilical cord has a pair of small umbilical arteries with deoxygenated blood and a single, large umbilical vein with oxygenated blood. Generally, arteries carry oxygenated blood and veins carry deoxygenated blood. This case is an exception where arteries carry deoxygenated blood and veins carry nutrient-rich oxygenated blood. Vein brings blood from the placenta to the foetus and arteries carry the waste back to the placenta. After one week of birth, the umbilical vein is completely obliterated and is replaced by a fibrous cord. It is genetically and physiologically a part of the foetus.
The placenta supplies oxygen supply and nutrients to the embryo and also facilitates the removal of carbon dioxide and excretory/waste materials produced by the embryo.
The umbilical cord has a pair of small umbilical arteries with deoxygenated blood and a single, large umbilical vein with oxygenated blood. Generally, arteries carry oxygenated blood and veins carry deoxygenated blood. This case is an exception where arteries carry deoxygenated blood and veins carry nutrient-rich oxygenated blood. Vein brings blood from the placenta to the foetus and arteries carry the waste back to the placenta. After one week of birth, the umbilical vein is completely obliterated and is replaced by a fibrous cord. It is genetically and physiologically a part of the foetus.