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
What causes hydrops fetalis and what are the symptoms associated with it?
This is a condition in which mother who has Rh negative blood type makes antibodies to her baby’s Rh positive blood cells, and the antibodies cross the placenta
Symptoms associated with this are large amounts of amniotic fluid buildup or fluid in the fetuses abdomen
What causes placenta previa and what are the symptoms associated with it?
When the placenta lies low in the uterus and partially or completely covers the cervix. The placenta may separate from the uterine wall as the cervix begins to dilate (open) during labor.
Associated symptoms include painless bleeding during the third trimester
What causes hydatidiform mole and what are the symptoms associated with it?
This is the growth of an abnormal fertilized egg due to an imbalance of genetic materials leading to an egg with no chromosomes or an egg fertilized by two sperm. Paternal imprinting.
Symptoms include abnormal growth of the uterus- either smaller or larger than usual
Define the congenital anomaly “malformation “
Primary errors of morphogenesis. They are usually multifactorial, involving a number of etiological agents including genetic and envinronmental factors
Define the congenital anomaly “disruptions “. Give an example.
Disturbances in otherwise normal morphogenetic processes. Examples include amniotic bands
Define the congenital anomaly “deformations “. What is this caused by? Give an example.
These are also disturbances in otherwise normal morphogenetic processes. These are typically caused by abnormal biochemical forces such as uterine constraints.
ex. clubfoot
Define the congenital anomaly “sequences “. Give an example.
A sequence is a series (cascade) of events triggered by on initiating factor (similar to the complement cascade)
Ex. oligohydramnios (decreased amniotic fluid) leading to fetal compression
Define the congenital anomaly “syndromes “
Constellations of congenital anomalies that are thought to be pathologically related but often caused by a single event such as a iral infection
What are the 3 causes of congenital anomalies?
Genetic
Environmental
Multifactorial
Describe the genotype, incidence rate, and characteristics of patients suffering from Turners Syndrome
Genotype: Aneuploidy- 45 complete chromosomes and one with one X chromosome
Incidence: 1 in 3000
Characteristics: Female with underdeveloped sex characteristics Low hairline Broad chest Sterile Normal intelligence level
Describe the genotype, incidence rate, and characteristics of patients suffering from Poly-X Syndrome
Genotype: XXX Incidence: 1 in 1000 Characeristics: Tall and thin Sterile Normal intelligence
What is the most common cause of neonatal mortality?
Congenital abnormalities- these were listed and described in earlier slides starting at slide 20
What is the second most common cause of neonatal mortality?
Premature and fetal growth restrictions
What are the major risks associated with prematurity?
Preterm premature rupture of placental membranes
Intrauterine infections
What are the 3 fetal factors that result in fetal growth restrictions?
Chromosome disorders
Congenital anomalies
Congenital infections
What are the 3 placental factors that result in fetal growth restriction?
Umbilical-placental vascular anomalies
Placenta thrombosis and infarction
Placenta previa
What are the 4 maternal factors that result in fetal growth restriction?
Preeclampsia
Chronic hypertension
Maternal use of drugs, narcotics, alcohol, and nicotine
Maternal malnutrition
What is neonatal respiratory distress syndrome?
This is related to the immaturity of the lungs and is related to premature birth. The more mature the fetus is the lower the chance they will develop this.
The cause is due to the lack of pulmonary surfactant.
What is fetal hydrops and what are the 2 types? What does immune hydrops cause for the mother and fetus?
The accumulation of edema fluid in the fetus during intrauterine growth.
Two types:
Immune hydrops
Nonimmune hydrops
Immune hydrops causes heolytic anemia due to blood group incomatibility between mother and fetus. Note that Rh is not an issue in the first pregnancy.
What 2 defects/abnormalities does nonimmune hydrops cause?
Cardiovascular defects such as congenital defects and and arrythmias
Chromosomal abnormalities- Turner syndrome and trisomies
What is Preeclampsia?
Pregnancy induced hypertension that develops after 20 weeks of gestation and returns to normal after birth
What 4 pathologies does Preeclampsia cause?
HTN
Proteinuria
Weight gain
Edema
What 2 symptoms does Eclampsia cause?
Extremely high bp
Grand mal seizures or coma
How does Thalidomide affect babies?
Limbs will not develop properly
How does retinoic acid affect babies?
Causes mental and physical deformities such as craniofacial malformations or abnormalities in the nervous system/cardiovascular system.
How does Folic Acid affect babies?
It prevents neural tube defects. In other words, it prevents brain and spinal cord deformities.
