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Embryo Exam II > Lecture 12 - Placental Physiology and Developmental Disorders > Flashcards

Lecture 12 - Placental Physiology and Developmental Disorders Flashcards

1
Q

What are the functions of the placenta?

A
  • diffusion of oxygen and carbon dioxide
  • diffusion of food stuffs
  • excretion of waste products
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2
Q

Early Placenta

A
  • thick
  • low permeability
  • small surface area
  • total diffusion conductance is minuscule
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3
Q

Late Placenta

A
  • Thin
  • High Permeability
  • Large Surface Area
  • Large increase in placental diffusion
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4
Q

Oxygen Pressure Gradient Near end of pregnancy

A

PO2 Mom- 50 mm HG

PO2 Fetus- 30 mm HG

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5
Q

Reasons why adequate oxygenation can occur with the low pressure gradient of Mom/Fetus:

A
  • fetal hemoglobin has higher affinity for O2
  • Fetal blood hemoglobin concentration is about 50% higher than maternal
  • Bohr Effect
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6
Q

Bohr Effect

A

Hemoglobin can carry more O2 at a low PCO2

  • fetal blood becomes alkaline —> can carry more O2
  • maternal blood becomes acidic —> decreased O2 affinity
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7
Q

Double Bohr Effect

A

Refers to the double shift in the maternal blood and the fetal blood

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8
Q

Other Placental Functions

A

CO2 diffusion
-PCO2 fetal > maternal

Diffusion of food

  • facilitated diff of glucose via trophoblastic cells
  • slower diffusion of fatty acids into fetal blood

Excretion of Waste Products
-urea, Uris acid, creatinine diffuse from fetus to maternal blood

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9
Q

Human Chorionic Gonadotropin

A

-secreted by syncytial trophoblast into maternal fluids

  • prevents involution of corpus luteum
  • causes CL to increase secretion of progesterone and estrogens
  • increased growth in CL
  • exerts interstitial cell-stimulating effect on testes of male fetus
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10
Q

Estrogens

A

Secreted by syncytiotrophoblast cells of placenta
Converted by trophoblast cells into estradiol, estrone, and estriol

  • uterine enlargement
  • breast enlargement
  • growth of breast ductal structure
  • enlargement of maternal external genitalia
  • relaxation of pelvic ligaments
  • may also affect aspects of fetal development
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11
Q

Progesterone

A

Secreted in small quantities by CL early
Secreted in large quantities by placenta

  • causes decidual cells to develop in the endometrium
  • decreases contractility of pregnancy uterus
  • increases secretions of Fallopian tubes and uterus
  • prepare breasts for lactation (along w estrogen)
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12
Q

Human Chorionic Somatomammotropin

A

Secreted by placenta beginning in the 5th week of pregnancy

  • causes decreased insulin sensitivity and decreased utilization of glucose by mother
  • metabolic hormone
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13
Q

Theories regarding placental immunology

A
  • lack of expression of major histocompatibility antigens
  • decidual immune barrier
  • inactivation of mother’s immune system components by molecules on fetal placental surface
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14
Q

Fetal Alcohol Syndrome

A

(Causes, symptoms)

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15
Q

Erythroblastosis fetalis

A

(Causes, symptoms)

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16
Q

Hydrophobic Fetalis

A

(Causes, symptoms)

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17
Q

Placenta Previa

A

(Causes, symptoms)

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18
Q

Hydatidiform mole

A

(Causes, symptoms)

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19
Q

What is the most common cause of neonatal mortality?

A

Congenital Anomalies

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20
Q

Malformation

A

Primary errors of morphogenesis

Usually multifactorial, involving a number of etiological agents including genetic and environmental factors

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21
Q

Disruptions

A

Disturbances in otherwise normal morphogenetic processes

Eg- amniotic bands

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22
Q

Deformations

A

Disturbances in otherwise normal morphogenetic processes. These are typically caused by abnormal biochemical forces such as uterine constraints.

Eg- club foot

23
Q

Sequences

A

Series (cascade) of events triggered by one initiating factor.

Eg- oligohydramnios (decreased amniotic fluid) which leads to fetal compression and other problems

24
Q

Syndromes

A

Constellations of congenital abnormalities thought to be pathologically related by cannot be explained on the basis of a single loci event. They are often caused by a single event such as oral infection.

25
Q

Why are developmental insults during the first three weeks of development unlikely to result in defective development?

A

See book

26
Q

Why are major structural anomalies unlikely to occur after the eighth week of pregnancy?

A

See book.

27
Q

What are the three main groups of congenital anomaly causes?

A

Genetic

Environmental

Multifactorial

28
Q

Preeclampsia

A

^^^ BP
Proteinuria
Weight gain
Edema

29
Q

Pregnancy induced hypertension

A

Persistent elevated BP (140/190) that develops after 20 wks gestation and returns to normal after birth

30
Q

Eclampsia

A

Extremely serious condition

Extremely high BP

Grand mal seizures or coma

31
Q

Nonimmune Hydrops

A

Major causes:

  • cardiovascular defects such as congenital defects and arrhythmias
  • chromosomal abnormalities
    • Turner syndrome and trisomy 21 or 18
    • generally due to cardiac structure aberrations that accompany these anomalies
32
Q

Immune Hydrops

A

Caused by blood group incompatibility between mother and fetus

  • fetal RBC reach maternal stream during last trimester or during childbirth
  • major factor is D antigen of Rh group
  • ABO incompatibility is generally not a problem with the 1st pregnancy

CONSEQUENCES OF RH DISEASE

33
Q

Kernicturus

A

SEE BOOK

34
Q

Fetal Hydrops

A

Accumulation of edema fluid in the fetus during intrauterine growth

Until recently the most common cause was hemolytic anemia caused by blood group incompatibility

Causes:

  • immune Hydrops
  • nonimmune Hydrops
35
Q

Neonatal Resp Distress Syndrome

A

Related to immature lungs —> premature birth

Incidence is inversely proportional to gestational age

Fundamental deficiency is lack of pulmonary surfactant

36
Q

Additional Developmental Problems

A

Prematurity and growth restrictions

Neonatal resp distress syndrome

Hydrops

Eclampsia

37
Q

Major risk factors of prematurity

A
  • preterm premature rupture of placental membranes
  • intrauterine infections
  • uterine, cervical, and placental structural abnormalities
  • multiple gestation
38
Q

Hazards of prematurity

A
  • hyaline membrane disease
  • necrotizing enterocolitis
  • sepsis
  • interventricular hemorrhage
  • long-term complications including developmental delay
39
Q

Fetal Factors resulting in fetal growth restriction

A
  • chromosome disorders
  • congenital anomalies
  • congenital infections
40
Q

Placental factors resulting in fetal growth restrictions

A
  • umbilical/placental vascular anomalies
  • placenta previa
  • placental thrombosis and infarction
  • multiple gestation
  • placental genetic mosaicism
41
Q

Maternal factors resulting in fetal growth restriction

A
  • Preeclampsia
  • Chronic hypertension
  • Maternal use of drugs, narcotics, alcohol, nicotine
  • Maternal malnutrition
42
Q

Gene Mutations

A

Include inborn errors of metabolism (rare).

Inherited most commonly as autosomal recessive or X-linked disease. A few are dominant.

Often affect enzymes and biochemical pathways.

Eg- phenylketonuria, galactosemia, cystic fibrosis

43
Q

Phenylketonuria

A

Congenital deficiency

Causes inadequate formation of L-tyrosine, elevation of L-phenylalanine, excretion of phenylpyruvic acid, and accumulation of phenylalanine

44
Q

Galactosemia

A

Congenital deficiency

Results in accumulation of galactose-1-phosphate

45
Q

Cystic Fibrosis

A

Inherited disorder (autosomal recessive) that affects mostly the lungs but also pancreas, liver, kidneys, and intestine.

Cystic fibrosis transmembrane conductance regulator (CFTR) gene

CFTR is a membrane pt chloride channel/transporter

46
Q

Chromosomal rearrangements

A

Deletions, duplications, inversions, translocation

47
Q

Changes in chromosome number

Aneuploidy

A

Changes in chromosome # from 2N state.

80-90% die in uterine in earliest stages of gestation

Trisomy 21, 13, Turner Sydrome, Poly-X syndrome

48
Q

Turner Syndrome

A

XO 1/3000

  • Female with underdeveloped sex characteristics
  • Low hairline
  • Broad chest
  • Folds on neck
  • Usually sterile
  • Normal intelligence
49
Q

Poly-X Syndrome

A

XXX 1/1000

  • Usually tall and thin
  • Often fertile
  • Normal intelligence
50
Q

Changes in chromosome number

Euploidy

A

Addition of a complete set of chromosomes in addition to diploid 2N stage

Often result of retention of a polar body of by fertilization by more than one sperm

Typically results in early spontaneous abortion

51
Q

Environmental Factors

A

Infection

Radiation

Maternal diabetes

Drugs and other chemicals

52
Q

Infections

A

Protozoans, bacteria

Viruses:
Rubella, herpes, varicella, influenza, mumps

53
Q

Drugs and other chemicals

A

Thalidomide

Alcohol

Retinoic Acid

Folic Acid

Embryo Exam II (8 decks)

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