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23 Cards in this Set

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  • Back
What are the fetal contributions to the placenta?
The chorion; Derivative of the trophoblast (plus fetal mesoderm); Cytotrophoblast & Syncytiotrophoblast
Which part of the fetal contribution contacts maternal blood?
Trophoblast (syncytiotrophoblast specifically)
Inner layer of the trophoblast
Outer layer of the trophoblast; Actively invades uterine wall; Outermost fetal component of the placenta; Increases SA for nutrient exchange
Chorionic villi
Facilitate fetal-maternal exchange; Invades & destroys uterine decidua (absorbing nutrients from it); Consists of trophoblast initially, then mesoderm (carrying umbilical vessels) grows in to vascularize them
What are the maternal contributions to the placenta?
Decidua & Uterine blood vessels (spiral arteries)
What is the decidua? How is it changed from endometrium? What is its role?
Uterine endometrial stroma; Cells swell and accumulate glycogen & lipids; Provides a physical & immunological barrier to invading trophoblast
What are the 3 layers of the decidua and where is each located?
Basalis (implantation site)Capsularis (enclosing the conceptus), and Parietalis (remainder of the uterus)
When does the trophoblast begin to invade the uterus?
Day 6
What is the difference between primary, secondary, and tertiary chorionic villi?
Primary: solid trophoblast
Secondary: mesoderm invades villous core
Tertiary: blood vessels penetrate mesoderm
Describe fetal circulation, starting w/ O2-poor blood.
O2 poor blood -> Umbilical aa -> Chorionic aa -> Chorionic villus caps -> Exchange -> O2-rich blood -> Chorionic veins -> Umbilical veins
Describe maternal placental circulation.
Spiral endometrial aa -> Lacunae -> Direct contact w/ syncytioTB -> Drained by endometrial vv
What happens to BP in the intervillous space? How much blood is there & how often is it replaced?
Reduced from 25mmHg to 15. 150mL blood in mature placenta. Blood supply replaced 3-4x/min
What happens when an increase in blood flow is needed?
Dilation of spiral aa by ingrowth of cytoTB/ endovascular TB
Placental transfer occurs across specialized regions of extremely thin fetal-maternal separations called __ __.
Epithelial plates
What waste products & other substances are removed from fetal circulation via the umbilical aa -> endometrial vv -> maternal lungs/kidneys?
CO2, H2O, urea, uric H+, bilirubin, RBC antiges, Hormones
What substances are nontransferable?
Bacteria, Heparin, Transferrin, IgS, IgM
What immune system things are transferrable from mom to baby?
Antibodies, IgG, Vitamins
What are the 3 accessory membranes? What is their origin?
Amnion, Yolk Sac, Allantois.
All are embryonic in origin.
Describe the amnion and its functions.
Avascular, Permeable to water. Suspends fetus in a liquid environment & fascilitates growth, mvt, & protects from injury
Where is the yolk sac located & what is its function?
Ventral to the embryo; Becomes incorporated into umbilical cord. Germ cell migratory route & embryonic hematopoiesis.
What is the allantois and what is its purpose?
Outpocket of the hindgut. Origin of germ cells/ respiration
Give 3 ways in which the fetus evades maternal recognition/rejection.
Maternal immunity is suppressed by tryptophan; The fetus masks foreign antigens w/ unique, non-classical MHC class I antigens; Barrier (local, physical, immune-based)