Conception and Prenatal Development

These flashcards cover key vocabulary related to conception and prenatal development, including the processes involved in conception, prenatal structures, and fetal circulation.

Conception

The process through which a sperm unites with an egg, leading to fertilization.

Ovulation

The release of a mature egg from the ovary for possible fertilization, occurring about 14 days before the next menstrual period.

Fertilization

The union of the sperm with the egg, occurring in the fallopian tube within 12-24 hours after ovulation.

Implantation

The attachment of the fertilized egg, or blastocyst, to the uterine wall, occurring approximately 6-11 days after fertilization.

Placenta

An auxiliary structure that permits the exchange of nutrients and waste between the maternal and fetal circulatory systems.

Umbilical Cord

A structure that connects the fetus to the placenta, facilitating nutrient and oxygen exchange.

Fetal Membranes

Two membranes (amnion and chorion) that protect and support the developing fetus.

Fetal Circulatory Circuit

The pathway of blood circulation in a fetus, including main structures like the ductus arteriosus, foramen ovale, and ductus venosus.

Foramen Ovale

An opening between the right and left atria of the fetal heart that allows blood to bypass the non-inflated lungs.

Multifetal Pregnancy

A type of pregnancy involving more than one fetus, which can occur from a single zygote or multiple zygotes.

Zygote

The single cell resulting from the union of a male sperm and a female ovum; the beginning of a new individual.

Blastocyst

A hollow ball of cells produced during early development (around day 5-6) that eventually implants in the uterine wall.

Amniotic Fluid

The liquid that surrounds the fetus in the amnion, serving to:

• Protect against trauma
• Maintain a constant fetal body temperature
• Allow for musculoskeletal development through movement

Ductus Arteriosus

A fetal blood vessel that connects the pulmonary artery to the aorta, allowing most blood to bypass the fetus's fluid-filled, non-functioning lungs.

Ductus Venosus

A shunt that allows oxygenated blood from the umbilical vein to bypass the liver and flow directly into the inferior vena cava.

Human Chorionic Gonadotropin (hCG)

A hormone produced by the placenta after implantation that maintains the corpus luteum to sustain the pregnancy; it is the hormone detected by pregnancy tests.

Embryonic Stage

The period of prenatal development from the beginning of the 3rd week through the 8th week after fertilization, during which all major organ systems are formed.

Fetal Stage

The period of prenatal development from the 9th week until birth, characterized by the continued growth and refinement of organs.

Monozygotic Twins

Twins that develop from a single fertilized ovum (zygote) that splits into two separate embryos; also known as identical twins.

Dizygotic Twins

Twins resulting from the fertilization of two separate eggs by two separate sperm during the same cycle; also known as fraternal twins.

Morula

A solid ball of cells, typically consisting of 12-16 cells, formed from the zygote by cleavage before it becomes a blastocyst.

Wharton's Jelly

A gelatinous substance within the umbilical cord that prevents compression of the blood vessels, ensuring a continuous supply of nutrients and oxygen to the fetus.

Viability

The capability of the fetus to survive outside the uterus, which is generally considered to be around 22-25 weeks of gestation.

Teratogens

Environmental substances or factors, such as drugs, radiation, or infections, that can cause structural or functional defects in a developing embryo or fetus.

Lanugo

The fine, downy hair that covers the body of the fetus, particularly between the 20th week and birth, helping to protect the skin.

Vernix Caseosa

A white, cheesy, protective substance that covers the fetus's skin to prevent it from becoming chapped or hardened by the amniotic fluid.

Surfactant

A substance produced in the fetal lungs that reduces surface tension in the alveoli, preventing lung collapse; adequate levels are crucial for respiratory transition at birth.

Decidua

The thick layer of modified mucous membrane that lines the uterus during pregnancy and is shed after childbirth; it forms the maternal side of the placenta.

Chorionic Villi

Microscopic, finger-like projections from the chorion that penetrate the decidua to establish the site of exchange between maternal and fetal blood.

Cotyledons

The functional units or segments of the placenta that contain groups of chorionic vill