3.1-3.4 Flashcards
the course of the prenatal period
Typical prenatal development, which begins with fertilization and ends with birth, takes between 38 -40 weeks and it’s divided into periods
-germinal period
-embryonic period
-fetal period
germinal period
what does it include?
occurs the first 2 weeks after conception
it includes:
-the creation of the zygote
-continued cell division
-attachment of the zygote to the uterine wall
layers of the cell
Blastocyst
trophoblast
blastocyst
the inner layer of the cell that develops into an embryo
trophoblast
the outer layer of the cell that provides nutrition and support to the embryo
the embryonic period
occurs 2 to 8 weeks after conception
-the mass of the cell is called an embryo
-organs start to appear
the three layers of the cell
-endoderm
-mesoderm
-ectoderm
endoderm
the inner layer of the cell that develops the respiratory and digestive systems
mesoderm
the middle layer of the cell which will become the circulatory system, reproductive system and excretory system
ectoderm
the outer layer of the cell which becomes the nervous system if the brain, sensory receptors, parts of the skin
life-support system of the embryo
amnion
umbilical cord
placenta
organogenesis
amnion
the sac containing the clear fluid which the developing embryo float
umbilical cord
it contains two arteries and one vein that connect the baby to the placenta
the placenta
it consists of a disk shape group of tissues in which small blood vessels from the mother and offspring intertwine
organogenesis
organ formation that takes place during the first two months of the prenatal development
the fetal period
it lasts about seven months, from between 2 months after conception and birth
the prenatal development
is also divided into three periods that are not: germinal, embryonic and fetal periods but this time we are calling them the 3 trimester
the brain development
Babies are born with 20 to 100 billion neurons—the nerve cells in the brain that handle information processing at the cellular level.
what are the four important phases of brain development in the prenatal period
*The neural tube;
* Neurogenesis;
* Neuronal migration; and
* Neural connectivity.
the neural tube
+ two birth defects resulted from the failure of the neural tube
it’s located in the embryo’s back
it’s formed about 18 to 24 days after conception
it closes from the top and bottom ends at about 27 days from conception
two birth defects resulting from the failure of the neural tube to close are anencephaly and spina bifida
neurogenesis
is the massive proliferation of new immature neurons, beginning at about week 5 and continuing through the remainder of the prenatal period
neural migration
the process of cells moving outward from their point of origin to their appropriate locations takes place between 6 and 24 weeks.
neural connectivity
at about the 23rd week, is when connections between neurons begin to occur
teratogen
any agent that can cause birth defects the field of study that investigates the cause of birth defect is called teratology
