Lecture 12 Placenta Physiology and Developmental Disorders

Question 1

List functions of the placenta.

Answer 1

• Diffusion of oxygen and CO2
• Diffusion of foodstuffs
• excretion of waste

Question 2

Compare the early placenta with the late placenta.

Answer 2

Early placenta is thick with low permeability, small surface area and total diffusion conductance is minuscule

Late placenta is thin with a high permeability and a large surface area with an increase in placental diffusion

Question 3

Describe the oxygen pressure gradient (near end of pregnancy) and explain why adequate oxygenation can occur with such a low pressure gradient .

Answer 3

The PO2 of the mother is 50mmHg and the PO2 of the fetus is 30mmHg

It can occur at a low pressure gradient because HbF has a high affinity for oxygen and it is highly concentrated in the blood

Question 4

Describe the Bohr effect.

Answer 4

hemoglobin is able to carry more oxygen at a low PCO2

any excess CO2 that comes from the fetus into the placenta is diffused into the maternal blood which causes and increase in the capacity for the fetal Hb to combine with O2

Question 5

Explain what is meant by the double Bohr effect

Answer 5

Double shift in the maternal blood and int eh fetal blood

Question 6

Describe the timing, method of secretion, targets, and effects of human chorionic gonadotropin

Answer 6

• secreted 8-9 days after ovulation by the syncytial trophoblast cells into the maternal fluids
  function: prevents involution of the corpus luteum and increases the amount of progesterone and estrogen secreted as well as increased CL growth
• if male fetus, helps stimulate the testes and produce testosterone until birth

Question 7

Describe the timing, method of secretion, targets, and effects of estrogens

Answer 7

secreted toward the end of pregnancy by the syncytiotrophoblast cells of the placenta from androgenic steroid compounds

functions: uterine enlargement, breast enlargement, growth of the breast ducts, relaxation of pelvic ligaments

Basically prep for the baby

Question 8

Describe the timing, method of secretion, targets, and effects of progesterone

Answer 8

secreted in small quants by the CL and in large quants by the placental

-causes endometrium development, decreased contractility of uterus, increased secretion, prep for lactation

Question 9

Describe the timing, method of secretion, targets, and effects of human chorionic somatomammotropin

Answer 9

Secreted in the 5th week of pregnancy

Functions: causes decreased insulin sensitivity and decreased utilization of glucose by the mother

metabolic

Question 10

Be able to describe each of the four theories discussed in lecture.

Answer 10

1. Lack of expression of major histocompatibility antigens by the syncytiotrophoblast and cytotrophoblast (protect the fetus from the mothers immune system-placenta components)
2. paralysis of the mothers immune system during pregnancy
3. Decidual immune barrier (prevent recognition by the mothers immune system that there is a foreign body in the uterine cavity)
4. inactivation of the mothers immune system (local-we are hiding the fetal placental surface from the mothers immune system)

Question 11

Define teratology

Answer 11

The scientific study of congenital abnormalities and abnormal formations

Question 12

Define teratogen

Answer 12

an agent or factor that causes malformation of an embryo

Question 13

Define malformations

Answer 13

primary errors of morphogenesis

multifactorial; involving numerous etiological agents with genetic and environmental factors

Question 14

Define disruptions

Answer 14

disturbances in otherwise normal morphogenic processes

include amniotic bands

Question 15

Define deformation

Answer 15

disturbances and otherwise normal morphogenetic processes. caused by abnormal biomechanics forces like uterine constraints

club foot

Question 16

Define dysplasia

Answer 16

the presences of cells of an abnormal type within a tissue, which can lead to the abnormal growth or development of a tissue or organ

Question 17

Define sequence

Answer 17

series of events triggered by one initiating factor

Question 18

Define syndromes

Answer 18

constellations of congenital anomalies that are pathologically related; usually caused by a single event like viral infection

Question 19

List and give approximate percentages of total, and examples of the three categories of causes of congenital anomalies.

Answer 19

Three groups: genetic, environmental, multifactorial

Unknown-50% 
Multifactorial- 25% 
Chromosomal-10% 
Monogenic- 8% 
Major environmental- 7%

Question 20

Define and give examples of gene mutations

Answer 20

inherited as autosomal recessive or X-linked diseases
-often effect enzymes and biochemical processes

Examples: phenylketonuria, galactosemia, cystic fibrosis

Question 21

Define phenylketonuria

Answer 21

congenital deficiency of The 4-monooxygenase. Causes inadequate formation of L-tyrosine, elevation of serum L-Phe, excretion of phenylpyruvic acid, and accumulation of Phe

Question 22

Define Galactosemia

Answer 22

congenital deficiency

tissue accumulation of galactose-1-phosphate

Question 23

Describe cystic fibrosis

Answer 23

inherited disorder that effects the lungs

autosomal recessive with mutations in the CFTR gene

Question 24

Define and give examples of chromosomal rearrangements

Answer 24

include deletions, duplications, inversions, and translocations

Aneuploidy- more chromosomes than you need;

turner syndrome, poly X syndrome

Question 25

Describe euploidy

Answer 25

addition of a complete set of chromosomes in addition to the diploid stage

retention of a polar body or by fertilization by more than one sperm

usually results in a spontaneous abortion

Question 26

Define and give examples of environmental factors

Answer 26

Infections caused by viruses (rubella), bacteria, protozoans, radiation, or diabetes

can be caused by drugs, alcohol, folic acid, etc

Question 27

Describe the effects of thalidomide on birth abnormalities

Answer 27

effects limbs; can cause the long bones to be misshapen

can also effect the eyes, ears, CV, GI, and kidneys

Question 28

Describe the effects of alcohol on birth abnormalities

Answer 28

Fetal alcohol syndrome; decreased mental ability, wide set and narrow eyes

Question 29

Describe the effects of retinoic acid on birth defects

Answer 29

malformations in the skulls, faces, limbs eyes, and CNS due to an increased vitamin A concentration

Question 30

Describe the effects of folic acid on birth abnormalities

Answer 30

can prevent abnormalities- if you dont have enough can lead to aencephaly

Question 31

What are the major risk factors of prematurity?

Answer 31

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

Question 32

What are the hazards of prematurity?

Answer 32

• hyaline membrane disease
• necrotizing enterocolitis
• sepsis
• intraventricular hemorrhage
• long term complications

Question 33

What are placental factors that results in fetal growth restriction?

Answer 33

• umbilical-placental vascular abnormalities
• placenta previa
• placental thrombosis and infarction
• multiple gestations
• placental genetic mosaicism

Question 34

What are maternal factors that result in fetal growth restriction?

Answer 34

• preeclampsia
• chronic HTN
• drug/alcohol abuse
• malnutrition

Question 35

Describe neonatal respiratory distress syndrome

Answer 35

baby can’t breathe because of immature lungs, usually due to an issue with surfactant

Question 36

Describe fetal hydrops

Answer 36

accumulation of edema in the fetus during intrauterine growth, blood group incompatibility can cause too