Placental Physiology and Disorders Flashcards
List functions of placenta.
- Diffusion of oxygen and carbon dioxide. PCO2 is 2-3x higher than maternal blood
- Diffusion of foodstuffs, facilitated diffusion of glucose via trophoblast cells, slower diffusion of fatty acids.
- Excretion of wastes such as urea, uric acid, and creatine to maternal blood
Compare early and late placenta.
- Early: thick, low permeability, small surface area, total diffusioin conductance is miniscule
- Late: thin, high permeability, large surface area, large increase in placental diffusion
Describe the oxygen pressure gradient near the end of pregnancy and why can adequate oxygenation occur with such a low pressure gradient?
- The mother has a PO2 of 50 mmHg and the fetus has a PO2 of 30mmHg.
- Even with a low pressure gradient adequate oxygenation can still occur due to fetal hemoglobin having higher affinity for oxygen than adult hemoglobin.
- Also due to Bohr effect.
Describe the Bohr effect.
Hemoglobin can carry more oxygen at a low PCO2, excess CO2 diffuses into maternal blood causing fetal blood to become more alkaline and maternal more acidic. Acidic gives up oxygen more easily and alkaline has higher affinity for it.
What is meant by the double Bohr effect?
Double Bohr effect refers to the double shift in the maternal blood and in the fetal blood.
Describe timing, secretion, effects and targets of HCG.
- Secreted: syncytial trohpoblast cells into maternal fluids, maximal secretion during 10th-12th week.
- Targets: CL and Interstitial cells.
- Function: Prevents involution of corpus luteum
- causes CL to increase progesterone and estrogen secretion
- increased CL growth
- exerts interstitial cell stimulating effects on testes of male fetus.
Describe timing, secretion, and targets, and effects of Estrogen.
- Secreted:synctiotrophoblast cells of placenta, 30X normal by end of pregnancy
- Targets and Effects:
- Uterine and Breast enlargement
- growth of breast ductal structures
- enlargement of external genitalia
- relaxation of pelvic ligaments and aspects of fetal development.
Describe timing, secretion, targets, and effects of progesterone.
- Secreted in small quantities by CL, Secreted large quantities by placenta.
- Effects/Targets:
- Causes decidual cells to develop into endometrium
- decreases contractility of uterus
- increases secretions of fallopian tubes and uterus
- may work with estrogen to prepare breasts for lactation.
Describe timing, secretion, targets, and effects of Human chorionic somatomammotropin.
Secreted: placenta during 5th week of pregnancy
Effects/Targets: Causes decreased insulin sensitivity and decreased utilization of glucose by mother, general metabolic hormone.
Describe theories as to why mothers immune system doesn’t recognize fetus as foreign.
- Lack of expression of MHC by syncytiotrophoblast and cytotrophoblast. (part of placenta)
- Paralysis of mothers immune system during pregnancy.
- Decidual immune barrier, essentially hides the baby, most likely best answer***
- Inactivation of mothers immune system components by molecules formed on fetal placental surface.
Review general principals on page 136.
2-3% of all newborns show at least one recognizable congenital malformation, and doubles when kids are diagnosed after birth.
Know causes of fetal alcohol syndrome and symptoms.
FAS
Causes and symptoms of erythroblastosis fetalis.
E
Placenta previa causes and symptoms.
d
Hydatidiform mole causes and symptoms.
d
What is Teratology?
Teratology
What is a Teratogen?
T
What is Malformation?
Primary errors of morphogenesis usually multifactorial involving a number of etiological agents including genetics and environmental factors.
Disruptions?
Disturbances in normal morphogenetic processes. For example amniotic bands, bands that get wrapped around limbs
Deformations?
Disturbances in normal developmental processes typically caused by abnormal biomechanical forces such as uterine constraints. Ex clubfoot.
Dysplasia?
D
Sequence?
Series of events triggered by one initiating factor. Example oligohydramnios causing fetal compression and other problems from the compression
Syndrome?
Constellations of congenital anomalies that are thought to be pathologically related but cant be explained by one initial event. Often caused by viral infections.
Association?
d
Critical period?
The susceptibility to attain congenital abnormalities, typically between 3-8 week of pregnancy
Why developmental insults during first three weeks of development are unlikely to result in defective development?
d
Explain why major structural anomolies are unlikely to occur after eighth week of pregnancy.
Major organs are typically developed at this point. Anomalies from 3rd-9th month are usually functional or disturbances of already formed body parts
h
Define compare and give examples of gene mutations with birth defects?
Inborn errors of metabolism, these are rare. They are inherited most commonly as autosomal rcessive or X linked. Few are dominant traits. Usually impact enzymes and biochemical pathways. Examples PK which is a deficiency of phenylalanine-4-monooxygenase it causes accumulation of phenylalanine and affects nervous system. Galactosemia results in tissue accumulation of galactose 1 phosphate. CF is autosomal recessive disorder in the CFTR protein gene which is a protein cl- channel.
Define compare and give examples of chromosome rearrangements with birth abnormalities?
Include deletions, duplications, inversions and translocation.
Define compare and give examples of changes in chromosome number with birth abnormalities?
Aneuploidy which is a change in chromosome number, 80-90% fetuses with this die in utero very early. Includes Trisomy 21, Trisomy 13, Turner syndrome, Poly-x-syndrome
Difference between aneuploidy and euploidy?
Euploidy is addition of a complete set of chromosmes in addition to the diploid stage, usually from retention of polar body or multiple sperm. Typically results in spontaneous abortion. Aneuploidy change in chromosome number
Give examples of infectious agents that can result in birth defects.
Radiation, Maternal diabetes, and infections from viral bacterial or protozoans.
Describe effects of thalidomide.
High incidence of limb defects
Describe the effects of Alcohol.
Book
Describe the effects of RA?
Earlier lectures referring to signaling pathways
Describe the effects of folic acid on birth abnormalities.
Can result in Neural Tube Defects such as ancephaly if deficient, could be related to nutritional deficienceies of mothers in late winter months.
Describe the causes and symptoms of neonatal respiratory distress syndrome.
Related to premature birth, inversely proportional to gestational age, Main deficiency is pulmonary surfactant which form from alveolar II cells keeps the walls of alveoli from sticking together occurs around 7 months of pregnancy, allows easy inflation of lungs
Describe the causes and symptoms of hydrops.
Accumulation of edema in fetus during intrauterine growth, most common cause used to be hemolytic anemia, others include immune hydrops and nonimmune
Describe the causes and symptoms of eclampsia.
Related to uterine contractions
Identify prematurity and fetal growth restriction as the second most common cause of neonatal mortality and list major risk factors of prematurity.
Preterem premature rupture of placental membranes Intrauterine infections Uterine, cervical, and placental structural abnormalities Multiple gestation
What is the most common cause of neonatal fatalities?
Congenital abnormalities, most likely to occur between 3rd-8th week of pregnancy
What are the three groups of causes of congenital anomalies and percentages?
- Genetic: 18% of anomalies
- Environmental: 7% of anomalies
- Multifactorial: 25%
- 50% is unknown
Turner Syndrome?
X0 total of 45 chromosomes not 46.
1 in 3,000 Female with underdeveloped sex characteristics
low hairline, broad chest, folds on neck, sterile, normal intelligence.
Poly-X-Syndrome?
XXX, 1 in 1,000 Usually tall and thin, often fertile, most have normal intelligence
Hazards of Prematurity?
Hyaline membrane disease, Necrotizing enterocolitis, sepsis, interventricular hemorrhage, long term complications including developmental delay
Fetal factors resulting in fetal growth restriction?
Chromosome disorders, congenital anomalies, congenital infections
Maternal factors resulting in fetal growth restricitons?
Preeclampsia chronic hypertension drugs alcohol malnutrition
Immune hydrops?
- Caused by blood group incompatibility between mother and fetus.
- Fetal blood enters mothers during birth and first baby is not impacted
- IgG is produced against blood type of first baby.
- Next babies will be impacted. Rhogam is given to destroy the Ab against babies blood type. D antigen is major factor.
Non-immune hydrops?
cardiovascular defects such as congenital cardiac defects and arrhythmias chromosomal abnormalities
List consequences of Rh disease?
Hemolytic anemia
Define kernicturus and describe consequences.
Yellowish staining of the fetal brain due to a build up of bilireuben
Preeclampsia?
Serious condition in which BP is higher than normal, proteinuria, weight gain, and edema occur.
Next stage is eclampsia which is sextrememly serious resulting in seizures or coma
