prenatal development and birth Flashcards
begins with fertilization and ends with birth
prenatal development
how long does prenatal development take?
between 266 and 280 days (38-40 weeks)
three periods of prenatal development
germinal, embryonic, fetal
takes place in the first two weeks after conception
germinal period
what happens during the germinal period?
creation of the zygote, continued cell division, and the attachment of the zygote to the uterine wall
takes place one week after conception
differentiation
what happens to the cells during differentiation?
specialization of cells to perform various tasks
consists of inner mass of cells that will eventually develop into the embryo
blastocyst
outer layer of cells that later provides nutrition and support for the embryo
trophoblast
implantation, the attachment of the zygote to the uterine wall, takes place about _____ to _____ after conception
11-15 days
occurs 2 to eight weeks after conception
embryonic period
rate of cell differentiation intensifies, support systems for cells form, and organs appear
organogenesis
the three layers of the embryo
endoderm
mesoderm
ectoderm
inner layer of cells which will develop into digestive and respiratory systems
endoderm
middle layer, which will become the circulatory system, bones, muscles, excretory system, and reproductive system
mesoderm
outermost layer, becomes the nervous sytem and brain, sensory receptors, and skin parts
ectoderm
the three life-support systems of the embryo
amnion
umbilical cord
placenta
sac that contains a clear fluid in which the developing embryo floats
amnion
contains 2 arteries and 1 vein, and connects the baby to the placenta
umbilical cord
disk-shaped group of tissues in which small blood vessels from the mother and offspring intertwine but do not join
placenta
in the ____ week after conception, the _____ that eventually becomes the spinal cord forms
third; neural tube
at about ____ days, ____ begin to appear, and at 24 days the cells for the ____begin to _____
21, eyes; heart, differentiate
lasts about seven months and is the prenatal period between two months after conception and birth in typical pregnancies
fetal period
refers to the chances of surviving outside the womb which begins at the end of the second semester
viability
long, hollow tube located on the embryo’s back; forms about 18 to 24 days after conception
neural tube
2 birth defects related to the neural tube
anencephaly and spina bifida
risk factors for the neural tube
maternal diabetes and obesity; secondhand smoke
four important phases of the brain’s development during the prenatal period
the neural tube
neurogenesis
neuronal migration
neural connectivity
generations of new neurons; 5th prenatal week to the end of the prenatal period
neurogenesis
cells move outward from their point of origin to their appropriate locations; 6-24 weeks after conception
neuronal migration
connections between neurons begin to occur; 23rd prenatal week
neural connectivity
any agent that can potentially cause a birth defect or negatively alter cognitive and behavioral outcomes
teratogen
field of study that investigates the causes of birth defects
teratology
the ____, ____, and the ____ to a particular teratogen influence both the severity of the damage to an embryo/fetus and the type of defect
dose
genetic susceptibility
time of exposure
how does dose effects influence severity of damage?
greater dose of agent=greater effect
the type or severity of abnormalities caused by a teratogen is linked to the genotype of the pregnant woman and the genotype of the embryo or fetus
genetic susceptibility
exposure to teratogens does more damage when it occurs at some points in development than at others
time of exposure
damage during the ______ period may even prevent ______
germinal; implantation
______period is more vulnerable than ______ period
embryonic; fetal
why is the probability of a structural defect greatest in the early embryonic period?
it is the time when organs are being formed
what sort of problems can teratogens cause during the fetal period?
stunt growth or to create problems in the way organs function
key teratogens
prescription drugs
non-prescription drugs
psychoactive drugs
prenatal care
medical care
prenatal programs
exercise
