Prenatal Development and Birth - Vocabulary Flashcards

Vocabulary flashcards covering key concepts from prenatal development and birth.

Zygote

Single cell formed by fertilization; the first stage of prenatal development from conception to implantation.

Blastocyst

A multicellular structure (60–80 cells) that implants and gives rise to the embryo and supporting tissues.

Implantation

Attachment of the blastocyst to the uterine wall, usually 7–10 days after conception.

Inner cell mass

Group of cells inside the blastocyst that develop into the embryo.

Trophoblast

Outer layer of the blastocyst that forms protective and nourishing tissues, eventually the placenta.

Amnion

Watertight sac surrounding the embryo with amniotic fluid for cushioning and temperature regulation.

Yolk sac

Early source of blood cell production in the developing embryo.

Chorion

Membrane that, with the placenta, surrounds the embryo and forms part of the placenta.

Placenta

Semipermeable organ that exchanges nutrients and gases between mother and fetus and mediates metabolic transactions.

Umbilical cord

Cord connecting fetus to the placenta, containing blood vessels for nutrient/waste exchange.

Embryonic disk

The region inside the blastocyst that gives rise to the embryo.

Endometrium

The uterine lining where implantation occurs and blood supply is established.

Period of the zygote

Conception through implantation (about 10–14 days).

Period of the embryo

From week 3 through week 8; organ formation begins and major structures develop.

Period of the fetus

From week 9 to birth; rapid growth and maturation of organs.

Ectoderm

Outer germ layer that forms the nervous system, skin, and hair.

Mesoderm

Middle germ layer that forms muscles, bones, and the circulatory system.

Endoderm

Inner germ layer that forms the digestive system, lungs, and urinary tract.

Neural tube

Early nervous system structure that becomes brain and spinal cord; forms by week 3.

Heartbeat

Cardiac activity that begins by about week 4 of gestation.

Rudimentary skeleton

Early skeleton development typically visible around week 7.

Sexual development (Y chromosome)

Presence of Y chromosome triggers testes development; absence leads to ovaries.

Neural tube formation milestone

Formation and closure of the neural tube around week 3.

Heartbeat milestone

Development of a detectable heartbeat around week 4.

Skeletal development milestone

Rudimentary skeleton forms around week 7.

Sexual development milestone (weeks 7–8)

Y chromosome triggers testes formation in males; ovaries form in females if no Y.

Age of viability

Gestational age at which a fetus can survive outside the womb with medical support (roughly 22–28 weeks).

Vernix

A protective coating that guards the fetus’s skin from chapping and aids moisture retention.

Lanugo

Fine fetal hair that helps vernix adhere to the skin.

Amniotic fluid function

Fluid cushions the fetus, regulates temperature, and allows movement in a buoyant environment.

Teratogen

Any agent that can cause birth defects or fetal damage.

Critical periods

Windows of development when specific organs are especially vulnerable to teratogens.

Rubella

German measles; maternal infection can cause serious defects; most dangerous in the first trimester; immunization advised.

Toxoplasmosis

Parasitic infection from undercooked meat or cat feces; can cause eye/brain damage or miscarriage.

Syphilis

STD that can harm the fetus; early treatment prevents harm; untreated can cause serious damage.

Genital herpes

Herpes infection that can cross the placenta or be transmitted during birth; C-section advised if active.

AIDS (HIV)

Virus transmitted perinatally; antiviral therapy reduces transmission risk.

Diethylstilbestrol (DES)

Synthetic estrogen once used to prevent miscarriage; linked to birth defects; discontinued.

Fetal Alcohol Syndrome (FAS)

Neurodevelopmental disorder from prenatal alcohol exposure; facial anomalies, microcephaly, heart defects.

Cigarette smoking

Maternal smoking exposes fetus to nicotine and carbon monoxide; linked to low birth weight and other problems.