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