Placenta and Developmental Disorders Flashcards
What are the 3 functions of the placenta?
Diffusion of oxygen and carbon dioxide
Diffusion of foodstuff- glucose via trophoblast cells and slower diffusion of fatty acids into fetal blood
Excretion of waste products- Urea, uric acid, and creatinine diffuse from fetus to maternal blood
Compare early versus late placenta in terms of: Thickness Permeability Surface area Diffusion rate
Early placenta:
- Thick
- Permeability low
- Small surface area
- Total diffusion conductance is minuscule
Late placenta:
- Thin
- Permeability high
- Large surface area
- Large increase in placenta diffusion
What is the oxygen pressure gradient near the end of the pregnancy in the mother and the fetus? What does this cause?
Mother’s PO2 is 50mmHg
Fetuses Po2 is 30mmHg
Fetal hemoglobin has a higher affinity for oxygen due to this difference in the oxygen pressure gradient, Bohr effect
Fetal hemoglobin is ____ more concentrated than the maternal hemoglobin
50%
Describe the Bohr effect. What does this cause to the fetal blood to become? What changes does this cause in fetal and maternal blood?
Fetal hemoglobin coming into the placenta is carrying more CO2 and diffuses into the maternal blood.
This causes fetal blood to become more alkaline and maternal blood to become more acidic.
These changes cause:
An increase in fetal blood combining with oxygen
A decrease in maternal blood combining with oxygen
What does syncytial trophoblast cells secrete?
Human Chorionic Gonadotropin
What are the functions of Human Chorionic Gonadotropin?
What does it prevent and what does it stimulate?
What does it cause in males? When does this affect stop?
Prevents involution of the corpus luteum
Causes CL to increase secretion of progesterone and estrogen
Causes CL to increase in growth
In males, it causes an increase in testosterone production until birth
What do syncytiotrophoblast cells of the placenta secrete?
Estrogen
What are the 5 functions of estrogen and its impacts on the mother?
Uterine enlargement Breast enlargement The growth of breast ductal structure The growth of maternal external genitalia Relaxation of pelvic ligaments
What 2 structures secrete progesterone? When and how much?
Corpus Luteum- early and in small quantities
Placenta- large quantities
What are the 3 functions of progesterone?
Causes decidual cells to develop in the endometrium
Decreases contractility of the pregnant uterus
Increases secretions of the fallopian tubes and uterus
What releases human chorionic somatomammotropin and when is it released?
Placenta at the 5th week of pregnancy
What is the function of human chorionic somatomammotropin?
Decreased insuling sensitivity and decreased utilization of glucose by the mother
What is one theory as to why the mother does not reject the fetus as it develops?
Because there may be a lack in the expression of MHC antigens by the syncitiotrophoblast and cytotrophoblast of the placenta, which could cause a paralysis of the mothers immune system during pregnancy
What causes fetal alcohol syndrome and what are the symptoms associated with it?
Heavy drinking during pregnancy
Is associated with physical malformations and behavioral/learning problems
What causes erythroblastosis fetalis and what are the symptoms associated with it?
This is caused by transplacental transmission of maternal antibodies to fetal RBCs, which causes an incompatibility between the mother and the fetal blood groups
Symptoms associated with this are hemolytic anemiain the fetus