Lecture 12 - Placenta II

Question 1

Glandular milk?

Answer 1

secretion from uterine glands in early pregnancy that enters intervillous space

Question 2

Premature blood flow and miscarraige?

Answer 2

increased blood flow in miscarraiges 7-11 weeks, no difference @ 12-13 weeks, distributed centrally and across placenta rather than flowing at periphery

Question 3

Villous cytotrophoblast?

Answer 3

trophoblast cel type found mainly in first trimester underlying the syncytiotrophoblast

Question 4

Syncytiotrophoblast?

Answer 4

single cell, surface layer of placenta formed by fusion of villous cytotrophoblast, does not replicate but is replaced by fusion of additional villous cytotrophoblast

Question 5

Extravillous cytotrophoblast?

Answer 5

differentiated cells that have migrated out of the villous placenta towards maternal tissue

Question 6

Structural changes of placenta during gestation?

Answer 6

stroma of villi become more cellular and vascularise (early), villous cytotrophoblast thins down (2nd trimester), villous cytotrophoblast is sparse (3rd trimester), branching of villi increases, then size of placenta increases

Question 7

Decidua parts (maternal contribution to placenta)?

Answer 7

decidua basalis (underly implantation site), decidua capsularis (overlay implantation site), decidua peritalis (around remainder of uterus)

Question 8

Decidua fusion?

Answer 8

as gestation progresses, amniotic cavity enlarges and compresses the uterine cavity, decidua capsularis fuses with peritalis

Question 9

Placenta membranes?

Answer 9

amnion (avascular, covers cord and placenta), chorion (fetal vessels)

Question 10

Umbilical cord?

Answer 10

formed from yolk sac, and allantois (which vessels are fromed from), 2 arteries 1 vein, Wharton’s jelly, myofibroblasts, mucopolysaccharides

Question 11

Placental adaptations to increase transport?

Answer 11

large villous surface area, syncytiotrophoblasts have microvilli for increased S.A, 3rd trimester most villi are samll tertiary villi and fetal capillaries are closley apposed to syncytiotrophoblast

Question 12

Placenta gas transfer?

Answer 12

greater affinity for oxygen Hbf, greater saturation at same pressure, also greater amount

Question 13

Bohr effect?

Answer 13

as maternal blood picks up fetal metabolites the pH drops, dropping affinity for oxygen; opposite effect for the etal blood therefore double Bohr

Question 14

The Haldane effect?

Answer 14

the capacity of hemoglobin to bind CO2 is related to amount of bound oxygen, therefore increases as maternal blood loses oxyge, opposite effect for fetus, double Haldane effect

Question 15

Functions of amniotic fluid?

Answer 15

buoyant medium allows symmetric growth, cushions embryo/fetus, prevents adhesion of fetus with membranes, allows fetus movement (muscle development), development of GI/respiratory tracts (swallowing/breathing)

Question 16

Source of amniotic fluid?

Answer 16

initially filtrate of maternal plasma, major fetal contribution, after 20 weeks primarily fetal urine

Question 17

Amniotic fluid recycling?

Answer 17

leaves mainly via fetal swallowing, moves across fetal skin prior to 24 weeks, across fetal membranes into maternal circulation (minor) and into fetal vessels of placenta and umbilical cord (major)

Question 18

Polyhydramnios?

Answer 18

excessive amniotic fluid due to impaired swallowing, found mainly in cases of diabetic pregnancy

Question 19

Oligohydramnios?

Answer 19

lack of amniotic fluid likely due to kidney problems

Question 20

Screening methods?

Answer 20

amniocentesis, chorionic villi sampling, cell-free fetal DNA flowing

Question 21

Diseases that placenta protects from?

Answer 21

hepB, rabies, measles, malaria (clogging however)

Question 22

Diseases that placenta does not prevent from?

Answer 22

HIV, small pox, rubella, toxoplasmosis

Question 23

Placenta and drug transport?

Answer 23

affects organogenesis (days 20-70 after LMP) - thalidomide (limb growth), diethylstillbestrol (cancer)

Question 24

Betamethasone?

Answer 24

glucocorticoid give to mother to prevent respiratory distress syndrome in fetus

Question 25

Drugs safe for fetus?

Answer 25

paracetamol, aspirin, heparin

Question 26

Drugs not safe for fetus?

Answer 26

alcohol, recreationals, warfarin