PLACENTA is a _______ organ that forms during pregnancy and serves the following FUNCTIONS:
Acts as an organ of _____ between maternal and fetal tissues, providing ______, ______, and _____ for the fetus.
The placenta produces the following hormones:
Finally, the placenta Serves as an ______ ______ between maternal and fetal tissues
Nutrition, respiration, and excretion
- hCG=human chorionic gonadotropin
- human placental lactogen=somatomammotropin
The placenta develops as the _____ (the _____ component) of the uterus is invaded by the embryo's trophoblast which forms _____ ____ (the _____ component)
Human placenta is hemochorial which means?
maternal blood comes in direct contact with the chorion
What is the endometrium located at the implantation site called?
The fetal surface of the placenta is characterized by the vascular _____ ____ covered by amnion, giving it a smooth, shiny grayish appearance, and the eccentrically attached _____ ____ that has 2 umbilical ______ and 1 umbilical _____ that are surrounded by _____ connective tissue called ____ ____.
- chorionic plate
- mucous CT
- Wharton's jelly
Umbilical vessels are _____ than the umbilical cord so they commonly twist around each other and sometimes ____ to form ____ known as ____ __.
The decidua is the ______ of the uterus in a pregnant woman. The three regions of the decidua are named according to their relation to the implantation site.
-The ______ _____ is the part of the decidua deep to the ______ (embryo and membranes) that forms the maternal part of the placenta
-The ____ ____is the superficial part of the decidua overlying the conceptus.
-The _______ _____ is all the remaining parts of the decidua.
What is the conceptus?
The embryo and membranes
What gives the maternal side of the placenta a cobblestone appearance? What are these separated by?
15-20 compartments, called cotyledons
The fetal component of the placenta is derived from the _____ and the ______ _____, forming the ______ _____.
During week 2, _____ _____ form within the synctiotrophoblast. ____ _____ near the synctiotrophoblast expand to form _____ _____ which ______ with the lacunae, filling them with blood. This process initiates the _____ ____ ____.
As these anastomoses develop, the cytotrophoblast initiates the formation of ____ _____.
maternal fetal circulation
The blood vessels formed in the tertiary villi make contact with capillaries that develop in the ____ ____ and ____ _____,which establish contact with the _____ _____. The cytotrophoblast cells in the ____ penetrate through the _____ _____ until they reach the _____. Here they contact similar extensions from neighboring villi and form the _____ ______.
The cytotrophoblast shell:
- Firmly attaches the _____ to the ______
- Is perforated by _____ _____ to supply and drain _____ from ______ ______.
- Degenerates by term and is replaced by _____ _____
chorion to the endometrium
blood from intervillous spaces
_____ _____ (______ ____)are those that extend from the chorionic plate to the decidua basalis (____ ____). ____ ____ will branch from the side of anchoring villi and represent sites where the _____ and ___ _____will occur between maternal and fetal blood.
- Stem villi (anchoring villi)
- decidual plate
- Terminal villi
- nutrient and gas exchange
The intervillous space of the placenta contains ____ ___
The placental membrane separates the _____ ____ from ____ ____. Think about it as the barrier that separates the maternal and fetal circulation; it is not an actual "membrane". Its structure changes throughout pregnancy.
Initially (by month 4), the outer surface of the ____ ___form a placental membrane that consists of 4 layers:
By the beginning of month 4, the ________ degenerates, leaving only 2 layers in the placental membrane:
maternal blood from fetal blood
2. Fetal endothelium
In the third trimester, the syncytiotrophoblast becomes very _____. Large pieces of it containing _____ ___ may break off as ____ ____ and enter the ____ _____; these enter the maternal circulation and are broken down in _____.
as synctial knots
Prior to week 8, ___ cover the entire surface of the chorion. As the pregnancy advances, however, chorionic villi on the _____ _____ continue to _____ to form the_____ _____ (___ ____). Chorionic villi on the _____ _____ degenerate and form a _____ _____ _____ by the end of month 3.
chorionic frondosum (bushy chorion)
smooth chorionic laeve
Clinical correlate: ____ ____ ____ is a ____ ____ (that occurs ______ or _________) of chorionic villus tissue for genetic testing and is performed around weeks ____
Chorionic villus sampling
transabdominal or transvaginal
During the 2nd week the _____ ____ appears on day 8 as fluid begins to collect between cells of the____ and overlying ____.
A layer of ____cells expands toward the embryonic pole and differentiates into a____ ____ separating the new cavity from the _______. This membrane is the lining of the amnion. Although the amniotic cavity is at first smaller than the _____ _____, it expands steadily.
By the ___ week, the amnion encloses the ____ ____.
The amnion becomes continuous with ___ at the attachment of the umbilical cord to the fetus (_____ ___ ___) and covers _____ _____ and _____.
epiblast and trophoblast
primitive umbilical ring
umbilical cord and placenta
Initially, amniotic fluid is secreted by cells of the____and some is derived from maternal ____, ____, and _____ ____ by diffusion. Beginning in the 11th week, the____contributes to the amniotic fluid by excreting ____ into the amniotic cavity. By late pregnancy, approximately ___ of fetal urine is added daily. Volume increases throughout pregnancy
30 mL at 10 weeks; 1000 mL at 37 weeks
maternal blood, tissue and interstitial fluid
AMNIOTIC FLUID CIRCULATION:
Amniotic fluid is _____ by the fetus and absorbed by the fetus's_______ and ______ ____. The fluid passes into the ____ _____ and the waste products in it cross the ____ _____ and enter the maternal blood in the _____ ____. Excess water in the fetal blood is excreted by the ____ _____ and returned to the amniotic sac through the____ ____ ____-.
respiratory and digestive tracts
fetal urinary tract.
As the volume of amnionic fluid increases, the amnion is pushed against the chorion and the ____ _____is obliterated such that the amnion lies against the ___ ____ to form the ______-_____ _____ (this is the "water-bag" that breaks prior to the delivery of the baby)
What are the functions of the amnionic fluid (5)?
Allows for fetal movements
Prevents adherence between amnion and embryo
Barrier to infection
Promotes lung development
What is amniocentesis? describe the process
a tyoe of analysis in which in a hollow needle is inserted through the mothers abdomen to the uterus and amniotic fluid is taken for analysis.
What is Amniotic bands/constriction ring syndrome?
Tears in the amnion may result in amniotic bands that encircle the fetal limbs or digits resulting in deformations
______ is the term for excess amniotic fluid. This is correlated with _____ _____ and disorders of _____ ____ _____ and _____ ______ (various atresias) that prevent the fetus from _______ amniotic fluid.
______ is too little amniotic fluid; may result from failure of the ____ ____ to form or amniotic fluid_____. Severe oligohydramnios early in pregnancy is a risk factor for ____ _______.
lung hypoplasia (lung underdevelopment)
Maternally derived cholesterol, triglycerides, phospholipids, ans Protein hormones like insulin, IgD, IgE, IgM ___ ___ cross the placenta