The Placenta Flashcards
What are the two layers that the outer cell mass differentates into?
Synctiotrophobals and cytotrophoblast
What happens to the emboryonic spaces?
The yolk sca disappears, and the amnitotic sac enlarges, and the choronic sca is occupied by the exanding amniotic sca, and the chornic membrane goes on to form the chornoci will
What are the main aims of implantation?
Establish the basic unit of exchange
Acnhor the placenta
Establish maternal blood flow within the placenta
What are the primary vili?
The early finger like projections of trophblast
What are the secondary villi?
The invasion of mesenchyme into the core
What are the tertiary villi?
The invasion of the mesenchyme core by fetal vessles
What is placenta praevia?
Implantation into the lower uterine segment, can cause haemorrhage in pregnancy and requires C section delivery, especially increase if the placenta grows across the internal os
What is decidulisation?
The decidual reaction provides the balacning force for the invasive force of the trophoblast, and this is not present in the ampulla of the fallopian tubes during an ectopic pregancy
What is the purpose of remodelling of the spiral ateries?
Creation of a low resistane vascular bed, and matains the hihg flow required to meet fetal demand
What happens to the blood vessels during pregancy?
They are lined by maternal endothelium, and are displaced by trophoblast to be lined by fetal tissue, and fetal tissue lines the spiral ateries to create low resistance high flow tissue
What is the placenta bordered with on the fetal side?
The chrononic plate
What is the placenta bordered with on the maternal side?
The decidua basalis
What are some of the features of a 1st trimester placenta?
Placenta is established, the placental barrier is still relatively thick and there is a complete cytotroblast layer between the synctiotrophoblast
What are some of the features of a full term placenta?
The surface area for exchange is dramatically increased, and the placental barrier is now thin, there is a cytotrophoblast layer below an synctitropbblast cells, and coteylons covered by a thin layer of dedicua basials are now recognisable and the grooves are formed by the decidual septa
What is the function of the umbilical ateries?
Carry deoxygenated blood from the fetus to the placenta
What causes pre ecalmpsia?
Trophoblastic disorder related to failed or incomplete differentation of the cytotrophoblast and the invasion of maternal blood vessels is rudimentary
What is the placenta involved in the synthesis of?
Glycogen, cholestrol and fatty acids
What are the protein hormones produced by the placenta?
Human chronic gonadttropin
Human chornoic somtotropin
Human chronoic thrytropin
Humna cortcion corticotropin
What are the steriod hormones produced by the placenta?
Progesterone and oestrogen
Where is HCG produced?
The synctiotrophoblast
What is the role of HCG?
Supports the secretroy function of the corpus letueum
How does progesterone affect maternal metabolism?
Increased appetite
What is the role of Hcs or hPL?
Increases glucose availablitiy to the fetus
What molecules move across the placenta down a concentration gradient?
Water, electrolytes, urea dn uric acid and gases
What molecules move by faciliated diffusion?
Glucose
How does gas exchnage occur across the placenta?
Simple diffusion, flow limited not diffusion limited
How does passive immunity occur across the placenta?
Fetal immune system is immature, and develops are a receptor mediated proccess that matures as pregancy progresses, and IgG passes across the placenta
Which is the immunoglobin that passess across the placenta?
IgG
What are some of the dysfunctions in antibody transport?
Hamelytic disease of the newborn , rheus group incompatibilty of the mother and the fetus
