Placenta, Amniotic Fluid and Umbillical Cord Flashcards
What is the placenta?
A temporary organ that forms when the chorion does. It develops villi to exchange oxygen and transfers substances between mother and fetus.
When does the placenta form?
When the trophoblast forms the chorion.
What is the embryonic portion of the placenta?
chorion frondosum
What is the maternal portion of the placenta?
decidua basalis
What is the decidua?
The endometrial lining of the uterine cavity.
What is the decidua basalis?
portion of the endometrium undelrying the implantation site.
What does the decidua capsularis cover?
the portion overlying the embryo; it separates it from the uterine cavity.
What is the decidua parietalis?
The remainder of the endometrium.
Where do villi develop on the fetal part of the placenta, and what do they do?
chorion fondosum; they allow for the exchange between maternal and fetal systems. Capillaries also form in this area.
What are the components of the exchange system?
amnion, chrionic plate, umbillical cord and basal plate.
Where do primary chorionic villi protrude from?
from the cytotrophoblast (they are segments of it) to the synciotrophoblast.
What do chorionic villi do?
give oxygen and nutrients from maternal blood to the fetus via diffusion; also diffuse from blood through the walls to the maternal blood.
What do tertiary chorionic villi contain?
embryonic blood vessesls; they connect with vessels in the chorion and connecting stalk to eventually (3rd week) circulate blood.
Fetal hemoglobin has a higher affinity for what?
Oxygen; is due to the short barrier that they must cross.
what is the placental membrane?
A membrane that allows substances to flow from the placenta into embryonic tissue. Oxygen, co2, glucose, fatty acids and vitamins are beneficial.
What are some dangerous things that cross the barrier?
Isotretinoin (acne medication), thalidomide, alcohol, illegal drugs, some viruses (e.g. herpes).
What is the Rh factor?
an antigen in blood cells. If the mother is Rh negative and the fetus is Rh positive, the mother will produce antibodies that could be harmful in a second pregnancy.
What are symptoms of Rh factor?
Swelling, collection of fluid in the tissues, jaundice, anemia.
How is Rh factor treated?
RhoGAM
What is the cotyledon
It contains large vessels that feeds into smaller placental vesicles. It ia section there are 20 - 25) of the decidius basalis. They contain chorionic villi and receive blood from chorionic vessels.
What is the purpose of chrionic villus sampling?
To test for genetic disorders from 10 - 20 weeks.
What is Wharton’s Jelly?
Connective tissue in the umbillical cord. IT increases in volume to allow closure of blood vessels.
Which umbilical vein regresses?
The right.
What does the left umbilical vein do?
delivers blood from the placentra to the fetus.
Why can a velamentous cord be dangerous?
more vessels are exposed to trauma during childbirth.
Where are normal placental implantation sites?
anterior, posterior and fundal (cranial position in uterus)
placenta previa
implantation of the placenta over the cervical os (opening).
placentra accreta
abnormal trophoblastic invasion into the muscular layer (increta) or the surrounding tissues (percerta).
What can the placenta synthesize
glycogen, cholesterol, fatty acids, nutrients and some globulin.
Where are most hormones syntheisized?
synciotrophoblast.
What hormone in the placenta induces lipolysis?
human placental lactogen/chorionic somatommammotropin; also known as the “growth hormone” of the fetus.
What does progesterone do?
maintains the endometrial lining during pregnancy and suppressed contractility in the uterine smooth muscle.
What is calcification?
A sign of placental aging; can affect the blood supply to the fetus. It is why pregnancies should not go too long past the due date.
What is the amniotic fluid?
Fluid surrounding the embryyo. It allows for symmetrial growth and movement (especially of lungs); it prevents infection, maintains homeostasis, and prevents sticking of the embryo to the amnion.
What is oligohydramnios?
A low volume of amniotic fluid associated with failure of kidneys and lungs to develop (potter syndrome).
What is polyhydramnios?
A high volume of amniotic fluid associated with CNS aomalies and closure of the esophagus or intestines.
What is amniotic band syndrome?
Tears in the amnion that detach and surround the fetus.
How are vessels formed?
Vasculogenesis or angiogenesis. (around the yolk sac and chorion)
What are blood islands?
Regions of the connecting stalk that eventually form vessels.
What is angiogenesis?
formation of vessels from existing vessels.
What organ of the fetus creates red and white blood cells?
the liver.
What cells that create RBC/WBC eventually become the liver?
aorta-gonad-mesonephros region (AGM) cells.
What do the umbilical veins and arteries do?
The umbilical vein carries oxygenated, nutrient-rich blood from the placenta to the fetus, and the umbilical arteries carry deoxygenated, nutrient-depleted blood from the fetus to the placenta
