COBGC Anatomy and Physiology 3 — Questions and Answers
Question 1: The placenta is derived primarily from which fetal tissue?
- Amnion
- Yolk sac
- Trophoblast (chorion) (Correct answer)
- Allantois
Correct answer: Trophoblast (chorion)
The trophoblastic cells of the early embryo differentiate into cytotrophoblast and syncytiotrophoblast, which form the fetal portion of the placenta.
Question 2: Human chorionic gonadotropin (hCG) is produced by which placental cell layer?
- Decidua basalis
- Syncytiotrophoblast (Correct answer)
- Cytotrophoblast
- Fetal vascular endothelium
Correct answer: Syncytiotrophoblast
The syncytiotrophoblast is the primary source of hCG, which maintains the corpus luteum and supports progesterone production in early pregnancy.
Question 3: A normal term pregnancy spans which gestational age range?
- 37–42 weeks (Correct answer)
- 36–41 weeks
- 38–42 weeks
- 37–40 weeks
Correct answer: 37–42 weeks
Term pregnancy is defined as 37 0/7 through 41 6/7 weeks of gestation, with early term (37–38+6), full term (39–40+6), and late term (41–41+6) subcategories.
Question 4: The normal umbilical cord contains how many vessels?
- One artery and one vein
- Two arteries and one vein (Correct answer)
- One artery and two veins
- Two arteries and two veins
Correct answer: Two arteries and one vein
A normal umbilical cord has two umbilical arteries (carrying deoxygenated blood from fetus to placenta) and one umbilical vein (carrying oxygenated blood to the fetus).
Question 5: Which decidual layer lies directly beneath the chorionic villi at the placental implantation site?
- Decidua parietalis
- Decidua capsularis
- Decidua vera
- Decidua basalis (Correct answer)
Correct answer: Decidua basalis
The decidua basalis underlies the implanted blastocyst and forms the maternal component of the placenta, contributing to the basal plate.
Question 6: In the second and third trimesters, amniotic fluid is primarily produced by which source?
- Amniotic membrane epithelium
- Fetal urine (Correct answer)
- Placental ultrafiltration
- Maternal serum transudation
Correct answer: Fetal urine
After approximately 16 weeks, fetal urine becomes the dominant source of amniotic fluid production, with fetal swallowing serving as the main resorption mechanism.
Question 7: The term 'lightening' in obstetrics refers to which physiological event?
- Decrease in fetal movement at term
- Descent of the fetal presenting part into the true pelvis (Correct answer)
- Spontaneous cervical ripening
- Increase in Braxton Hicks frequency
Correct answer: Descent of the fetal presenting part into the true pelvis
Lightening describes engagement — the descent of the fetal presenting part (usually the head) into the maternal pelvis, which often relieves upper abdominal pressure but increases pelvic pressure.
COBGC Anatomy and Physiology 3
The placenta is derived primarily from which fetal tissue?