This is accomplished by the circulation of the baby's blood through the body stalk, which develops into the umbilical cord. This cord has two arteries leading from the baby to the placenta, and a vein from the placenta to the baby. These blood vessels branch out into the placenta like a group of trees, and leaf-like "fingers" made up of cells surround these branches. The mother's blood flowing by means of other blood vessels from the womb wall into the placenta bathes these "fingers" so that they can dispose of wastes from the embryo and pick up nourishment to carry back through the umbilical cord to the baby.
The placenta serves the baby as lungs, liver, kidneys and intestines until the baby enters the world to be on its own. The placenta also performs some of the functions of a hormone gland. Additionally it produces substances that can combat infections.
In doing the work of a lung the placenta exchanges carbon dioxide from the baby's bloodstream for oxygen from the mother's. As a "kidney" the placenta filters urea out of the baby's blood and transfers it to the mother's blood, where it is passed out through her kidneys. As a "liver," the placenta processes some of the mother's blood cells, transferring certain necessary components, such as iron, to the baby's circulatory system. In performing the functions of intestines the placenta digests the food molecules by means of enzymes. These exchanges are made through the pores of the embryo's branched-out blood vessels. The placenta also does a work similar to the glands by producing certain hormones, both for the baby and for the mother. It serves to protect the baby by manufacturing certain blood ingredients that prevent infection. All of this enables the baby to function fully on its own and prepares it to do all these things for itself after birth.
The placenta serves the baby as lungs, liver, kidneys and intestines until the baby enters the world to be on its own. The placenta also performs some of the functions of a hormone gland. Additionally it produces substances that can combat infections.
In doing the work of a lung the placenta exchanges carbon dioxide from the baby's bloodstream for oxygen from the mother's. As a "kidney" the placenta filters urea out of the baby's blood and transfers it to the mother's blood, where it is passed out through her kidneys. As a "liver," the placenta processes some of the mother's blood cells, transferring certain necessary components, such as iron, to the baby's circulatory system. In performing the functions of intestines the placenta digests the food molecules by means of enzymes. These exchanges are made through the pores of the embryo's branched-out blood vessels. The placenta also does a work similar to the glands by producing certain hormones, both for the baby and for the mother. It serves to protect the baby by manufacturing certain blood ingredients that prevent infection. All of this enables the baby to function fully on its own and prepares it to do all these things for itself after birth.