Lecture Notes: Human Development - Fertilization, Prenatal Stages, and Gene-Environment Interactions

Vocabulary flashcards covering fertilization, prenatal stages (germinal, embryonic, fetal), gestation terms, key anatomical structures, and basic genetics concepts referenced in the notes.

Fertilization

Union of a sperm and an egg forming a zygote; the egg's surface hardens after the first sperm enters to prevent additional sperm.

Zygote

Fertilized egg that begins dividing as it travels toward the uterus and eventually implants.

Germinal stage

First prenatal stage (roughly weeks 1–2); fertilization, cell division, and implantation in the uterus.

Blastocyst

Early hollow ball of cells formed after zygote division; implants in the uterine wall.

Placenta

Organ that develops during pregnancy to transfer nutrients and remove waste between mother and fetus.

Amniotic fluid

Fluid surrounding the developing embryo/fetus that protects and cushions development.

Embryonic period

Most critical period for environmental exposure; organ and body structure formation.

Fetal stage

From about week 9 to birth; organs mature, growth occurs; the fetus can hear; typical birth weight around six pounds.

Gestation

The period of development from conception to birth; roughly 40 weeks.

Gestational age

Estimated fetal age based on last menstrual period to project due date and track development.

Conception

Process initiating pregnancy with fertilization and implantation.

Critical period

Early prenatal weeks when environmental exposures can cause serious developmental effects.

Teratogen

An environmental agent that can cause birth defects or developmental problems.

Gene

A basic unit of heredity located on chromosomes that codes for a trait.

Allele

One form of a gene; different alleles explain variations in inherited traits.

Homozygous

Having two identical alleles for a gene.

Heterozygous

Having two different alleles for a gene.

Carrier

An individual with one recessive allele who may pass it to offspring but does not express the trait.

Chromosome

A structure carrying many genes and alleles; located in the cell nucleus.

Gene-environment correlation (passive)

A correlation where the child has little control; parents’ genetics influence the environment provided.

Birth weight

Weight of the newborn; around six pounds or more at term.