Fetal Growth and Development - Chapter 12

Vocabulary-style flashcards covering fetal development stages, placental structures, circulatory shunts, and amniotic fluid functions based on the lecture material.

Conception

The union of a single egg and a single sperm, forming part of a sequential process rather than an isolated event.

Morula

A $16-cell$ mass produced by mitotic divisions of the zygote within $24$ hours of ovulation.

Human gestation

A period lasting approximately $280\,days$ after the last menstrual period or $266\,days$ after conception.

Implantation

The process where the embryo attaches to the uterine lining, beginning $6\,days$ after fertilization.

Placenta

The organ of exchange between mother and fetus that develops from chorionic villi and is fully functional by $10\text{--}12\,weeks$.

Umbilical Arteries

The $2$ vessels in the umbilical cord that carry waste products away from the fetus to the placenta.

Umbilical Vein

The $1$ vessel in the umbilical cord that carries oxygenated blood from the placenta to the fetus.

Wharton’s jelly

A specialized connective tissue that protects the three vessels within the umbilical cord.

Chorionic villi

Fingerlike projections that increase surface area to allow gas exchange, nutrient transfer, and waste removal without mixing maternal and fetal blood.

Amniotic Fluid

Fluid that protects the fetus from trauma, maintains constant temperature, allows movement for development, and serves as a source of oral fluid and waste repository.

Foramen ovale

A fetal circulatory shunt that allows blood to flow directly from the right atrium to the left atrium, bypassing the lungs.

Ductus arteriosus

A fetal circulatory shunt that connects the pulmonary artery to the aorta, bypassing the lungs.

Ductus venosus

A fetal circulatory shunt that connects the umbilical vein to the inferior vena cava, bypassing the liver.

Embryonic Period

The developmental stage from weeks $1\text{--}8$ characterized by organogenesis and the highest vulnerability to teratogens.

Fetal Period

The developmental stage from weeks $9\text{--}40$ focused on the growth and maturation of systems.

Quickening

The first fetal movements felt by the mother, which typically occur at week $20$.

Viability

The point in fetal development when survival outside the uterus is possible, typically reached by week $24$.

Surfactant

A substance required for lung development that begins production at approximately $24\,weeks$ and is adequate by weeks $34\text{--}36$.

Meconium

The first fetal stool that forms in the gastrointestinal system as the fetus swallows amniotic fluid.

Dizygotic twins

Fraternal twins resulting from the fertilization of $2$ eggs by $2$ sperms, having separate amnions, chorions, and placentas.

Monozygotic twins

Identical twins resulting from $1$ fertilized egg that splits in two; they may share a chorion and placenta depending on when the division occurs.

Teratogens

External agents such as alcohol, tobacco, or infections (TORCH) that have the greatest effect on the embryo between days $15$ and $60$.

Organogenesis

The process of organ formation that occurs during the embryonic period (Weeks $1\text{--}8$).

IgG transfer

The process of providing immune protection to the fetus that increases significantly during the third trimester.