Conception, Fetal Development, and Hormonal Regulation

Which specific tissue secretes Human Chorionic Gonadotropin (HCG) early in pregnancy?

The trophoblast.

What is the primary function of HCG during the first 20 weeks of pregnancy?

Stimulating the corpus luteum to produce progesterone and estrogen.

Around which days of gestation does the concentration of HCG typically peak?

Day 50 to 70.

Human placental lactogen (hPL) is also known by what alternative name?

Human chorionic somatomammotropin (hCS).

Human placental lactogen (hPL) acts as a(n) _____ antagonist to increase maternal resistance.

Insulin.

Which hormone facilitates the transport of glucose across the placental membrane for fetal use?

Human placental lactogen (hPL).

Which hormone is responsible for softening the cervix and remodeling collagen during pregnancy?

Relaxin.

Which hormone is characterized as a 'true pregnancy hormone' that inhibits uterine activity and diminishes contraction strength?

Relaxin.

By which week of pregnancy does the placenta begin producing estrogen?

The 7th week.

Estrogen stimulates the development of the _____ system within the breasts to prepare for lactation.

Ductal.

How do endogenous and exogenous estrogens affect the blood coagulation system?

They increase fibrin and coagulation factors while decreasing fibrinolysis.

Estrogen physiology involves an increase in which four specific coagulation factors?

Factors II, VII, VIII, and X.

Which hormone plays the greatest role in maintaining the endometrium or decidua to sustain pregnancy?

Progesterone.

Progesterone prepares the breasts for lactation by developing the _____ cells and lobules.

Acini.

What is the primary gastrointestinal risk associated with high levels of endogenous progesterone?

Slowing of the GI system leading to constipation and nausea.

In which specific part of the female reproductive system does fertilization typically occur?

The outer third of the fallopian tube.

For how long after ovulation is a human ovum considered fertile?

Approximately 24 hours.

What is the term for the process of removing the sperm's protective coating?

Capacitation.

A _____ is a developmental stage of the embryo consisting of 16 cells.

Morula.

The two main components of a blastocyst are the embryoblast and the _____.

Trophoblast.

How many days after conception does implantation typically begin?

6 to 10 days.

What is the term for the former endometrium once the embryo has implanted?

Decidua.

Gestation is typically calculated as _____ days from the first day of the last menstrual period (LMP).

280

The embryonic stage of development lasts from day 15 until _____ weeks after conception.

8

What term refers to substances or exposures that cause abnormal fetal development?

Teratogens.

Amniotic fluid volume of less than 300 ml is clinically termed _____.

Oligohydramnios.

Amniotic fluid volume exceeding 2 liters is clinically termed _____.

Polyhydramnios (hydramnios).

What is the primary function of Wharton's jelly within the umbilical cord?

To surround the vessels and prevent compression.

The umbilical cord typically contains _____ artery/arteries and _____ vein(s).

2; 1.

Which structure aids in transferring maternal nutrients and oxygen to the embryo for the first 5 to 6 weeks?

The yolk sac.

By which week of gestation is the structure of the placenta considered complete?

The 12th week.

List the four main hormones produced by the placenta acting as an endocrine gland.

HCG, hPL (hCS), progesterone, and estriol.

What are the four primary metabolic functions of the placenta?

Respiration, nutrition, excretion, and storage.

The stage of the fetus begins at _____ weeks of gestation.

9

Fetal hemoglobin has a high affinity for oxygen and carries _____ % more oxygen than maternal hemoglobin.

20% to 30%.

In which week of development does hematopoiesis (blood formation) begin?

The 3rd week.

What clinical measurement is used to determine fetal lung maturity?

L/S ratio.

What is the name of the first fetal or newborn stool?

Meconium.

The fetal kidneys form during week 5 and begin to function by week _____.

9

From which of the three primary germ layers does the neurologic system originate?

Ectoderm.

By which week of gestation does a fetus typically begin to respond to sound?

24 weeks.

During which week of gestation does sex differentiation begin?

The 7th week.

Which immunoglobulin class is able to cross the placental barrier from the mother to the fetus?

$IgG$.

Which immunoglobulin class does the fetus produce itself?

$IgM$.

_____ twins result from multiple mature ova being fertilized, resulting in two separate zygotes.

Dizygotic.

_____ twins result from a single fertilized ovum that divides.

Monozygotic.

What is the primary cause for the increase in multiple births in the United States?

Increased use of assisted reproductive technology (ART).

In the umbilical cord, the umbilical _____ carries oxygenated blood from the placenta to the fetus.

Vein.

The three vascular shunts unique to the fetal circulatory system are the ductus arteriosus, ductus venosus, and _____.

Foramen ovale.

Which specific type of endogenous estrogen is produced by the liver of a fetus during pregnancy?

Estetrol.

What is the medical term for the fine, downy hair covering the fetal body?

Lanugo.

At what maternal age does the frequency of dizygotic twinning typically peak?

37 years.

According to the sensitivity chart, the fetal heart is considered 'highly sensitive' to teratogens between weeks _____ and _____.

3; 6.

Which germ layer gives rise to the musculoskeletal and cardiovascular systems?

Mesoderm.

Which germ layer gives rise to the epithelial linings of the digestive and respiratory tracts?

Endoderm.

Conjoined twins occur when the cleavage of a single ovum is _____ and occurs late.

Incomplete.

Which hormone acts as a smooth muscle relaxant to prevent the uterus from contracting prematurely?

Progesterone.

Estrogens increase the risk of _____ by increasing coagulation factors and decreasing fibrinolysis.

Deep vein thrombosis.

Amniotic fluid helps maintain fetal _____ to provide a stable thermal environment.

Thermoregulation.

The fetal stage is recognized as starting when the fetus becomes recognizable as a _____.

Human being.