growth
an increase in size
development
the continuous process by which an individual changes from life phase to another
prenatal period
begins with fertilization and ends at birth
postnatal period
begins at birth and ends at death
prenatal and postnatal
what are the 2 life phases
pregnancy
the presence of developing offspring in the uterus
3 month periods during pregnancy
trimesters
pregnancy results from the union of an egg cell and a sperm cell called
fertilization
the first cell of the future offspring
zygote
About 30 hours after forming, the zygote undergoes mitosis, giving rise to 2 new cells called
blastomeres
phase of early rapid cell division
cleavage
the offspring is termed_____ until the end of the 8th week
an embryo
After the 8th week and until birth, the offspring is called
a fetus
The cells surrounding the embryo, with cells of the endometrium, form a complex vascular structure called
the placenta
a hormone that indicates pregnancy
Human Chorionic Gondatropin
stimulates breast development and prepares the mammary glands for milk secretion
placental lactogen
where all cell organs form from the 3 cell layers
primary germ layers
3 cell layers
ectoderm, endoderm, and mesoderm
projections that grow out from the trophoblast into the surrounding endometrium
chorionic villa
develops around the embryo during the 2nd week and attaches around the edge of the embryonic disk, and amniotic fluid fills the space between the amnion and embryonic disk
amnion
3 blood vessels that transport blood between the embryo and the placenta
2 umbilical arteries and 1 umbilical vein
begins at the end of the 8th week of development and lasts until birth
fetal stage
an opening in the atrial septum called the
foramen ovale
continues for 38 weeks from conception, which is 40 weeks from the womans last period
pregnancy
stimulates powerful contractions
oxytocin
bleeding accompanies the expelled placenta termed
the afterbirth
twins resulting from 2 sperm cells fertilizing 2 egg cell
dizygotic twins
twins resulting from one sperm cell fertilizing one egg cell
monozygotic twins
occuring after birth
postpartum