Placenta Flashcards
Explain the function of the placenta
It is responsible for maintaining a pregnancy
produces hormones
produces glycogen
transport across the placenta
immunity passed to fetus
immunological tolerance of fetus as an allograft
What things cross the placenta?
Water Urea & Electolytes Bilirubin Gases & glucose IgG Amino acids Iron, Calcium Vitamins
What hormones are synthesised by the placenta?
Oestrogen Progesterone HpL HCG HCC HCT
What is the function of human chorionic gonadotrophin?
Supports corpus luteum
Produces steroid hormones
Prevents regression of corpus luteum
In what other circumstances is hcg secreted?
Testicular cancer
What affects diffusion across the placenta?
Gradient
Distance
Barrier
What teratogens can cross the placenta?
Warfarin Anti-convulsants Thalidomide Alcohol Smoking NSAIDs
What infections can cross the placenta?
Varicella Zoster Chicken Pox cytomegalovirus Toxoplasma gondii Rubella
Explain the immune function of the placenta
transfer of IgG to fetus by passive immunity expresses unique MHC class I to protect fetus as an allograft no MHC class II receptors on placenta
What other things may help with immunosuppression and protection of the fetus?
Prolactin
Progesterone
Explain haemolytic disease of the newborn
If a mother has had a previous child with the rhesus blood group, then she will have antibodies against the blood group. If she then concieves again, and this fetus has the rhesus blood group the maternal immune system will attack the fetus’s rbc and cause haemolytic anaemia and reticulocytosis
Explain the structure of the placenta
Maternal portion - decidua basalis and surrounded by amnion
Fetal portion - chorionic frondsum
How does the umbilical cord insert into the placenta?
Perpendicularly
What occurs when a mother’s water breaks
The amnion bursts and there is a leakage of amniotic fluid
What are the properties of the first trimester placenta?
Thick due to cytotrophoblast underneath
