Anatomy and Physiology Flashcards

The placenta is derived primarily from which fetal tissue?

Answer: Trophoblast (chorion)

The trophoblastic cells of the early embryo differentiate into cytotrophoblast and syncytiotrophoblast, which form the fetal portion of the placenta.

Human chorionic gonadotropin (hCG) is produced by which placental cell layer?

Answer: Syncytiotrophoblast

The syncytiotrophoblast is the primary source of hCG, which maintains the corpus luteum and supports progesterone production in early pregnancy.

A normal term pregnancy spans which gestational age range?

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.

The normal umbilical cord contains how many vessels?

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).

Which decidual layer lies directly beneath the chorionic villi at the placental implantation site?

Answer: Decidua basalis

The decidua basalis underlies the implanted blastocyst and forms the maternal component of the placenta, contributing to the basal plate.

In the second and third trimesters, amniotic fluid is primarily produced by which source?

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.

The term 'lightening' in obstetrics refers to which physiological event?

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.