ⓘ Placenta. The placenta is a temporary organ found in eutherian female mammals while they are pregnant. The placenta is connected to the fetus by the umbilical c ..


ⓘ Placenta

The placenta is a temporary organ found in eutherian female mammals while they are pregnant.

The placenta is connected to the fetus by the umbilical cord, which is made of blood vessels and connective tissue. When the fetus is delivered, the placenta is delivered afterwards. The placenta is often called the afterbirth.


1.1. Function The placenta protects the mother and fetus

One of the placentas jobs is to make sure blood from the mother and fetus never mixes. The placenta acts as an exchange surface between the mother and the fetus. Nutrients and oxygen are passed over by diffusion only. If the mothers and fetuss blood mixed, it could be deadly for both of them. If the mother and the fetus had different blood types, they might both die if their blood mixed.


1.2. Function The placental barrier protects the fetus

The placenta has two parts, one of which is genetically and biologically part of the fetus, the other part of the mother. It is implanted in the wall of the uterus, where it receives nutrients and oxygen from the mothers blood and passes out waste. This forms a barrier called the placental barrier, which filters out some substances which could harm the fetus.

However, the placental barrier is not able to protect the fetus from everything that could hurt it. For example, alcohol goes through the placental barrier into the fetus. This is why drinking alcohol during pregnancy can cause Fetal Alcohol Syndrome. The placenta is also unable to filter out many other things. Chemicals that can cross the placental barrier and hurt the fetus are called teratogens.

Some infectious diseases may also cross this barrier and infect the fetus.


2. In other types of mammals

Prototherial egg-laying and metatherial marsupial mammals produce a type of placenta that provides nutrients mostly from the egg sac, instead of from the mothers blood. It is positioned in the females body similar to eutherian mammals. Some snakes and lizards have evolved a system of internal development with a placenta-like tissue: this is an example of convergent evolution.

  • small amount by the liver, adrenal cortex, and breast. In pregnancy, the placenta can also have a lot of secretion. Male testes also secrete a small amount
  • mammals. This means that a Eutherian fetus is fed during gestation by a placenta The offspring of Eutherians are carried in the mother s uterus until fully
  • mother. The key idea is that the growing embryo gets its nutrition from a placenta in the mother s womb. It is the standard method for all mammals except
  • transfer nutrients over larger distances spinal cord Umbilical cord, a tube that connects a developing embryo or fetus to its placenta Vibrating string Chord
  • rapid coordinated contraction of muscles along their entire length. The placenta of mammals is a syncytium. King R.C. Stansfield W.D. & Mulligan P.K. 2006
  • problems like cancer of the uterus To take out tissues from a fetus or placenta after a miscarriage or a medical abortion, which will stop bleeding Mayo
  • mentions three kinds of cakes - libum, savillum, and placenta - for use as offerings to the gods. Placenta cakes were the closest to today s cheesecakes, since
  • a needle is inserted - for example, to get a sample of fluid from the placenta Prenatal tests can check for many conditions, like: Down syndrome Spina
  • and the embryo then develops inside the uterus, being fed by the mothers placenta The ovum is the largest cell in the human body. You can see it without
  • birth through the wall of the abdomen. Afterbirth is the birth of the placenta following the birth of the baby. Birth canal is the term used for the vagina