DEP3103
Test 2
Chapter 4
Prenatal Development and Birth
·
Stages
of Development- Early Embryo:
o
Once
every 28 days, in the middle of the menstrual cycle, an ovum is going to burst
from the ovary and get pulled into the fallopian tube. After it travels through
the fallopian tube, it moves to the uterus. If the egg doesn’t implant, 2 weeks
later the uterus lining is discarded, and there is a period.
o
Males
produce on average about 300 million sperm per day. Sperm can live up to 6 days
inside the female and wait for the ovum to be released.
o
Most
pregnancies occur when you have intercourse during a three day period- 2 days
before ovulation and the day of ovulation.
·
The
Germinal Period- The period of the zygote, it lasts from conception to about 2
weeks.
o
The
end of this period is characterized by implantation, when the zygote implants
into the uterine wall.
·
The
Embryonic Period- The period of the embryo, it lasts from 2 to about 8 weeks.
o
It
is characterized by the life systems developing and organ development.
o
Life
systems:
1.) Amnion- a sac where the baby lives inside the uterus,
has amniotic fluid in it, and protects the baby from drastic temperature
changes.
2.) Umbilical cord- contains 2 arteries and 1 vein, connects
the baby to the placenta, typically 1 to 3 feet long
3.) Placenta- disk-shaped group of tissue, where small blood
vessels from the mom and the baby intertwine, permits food and oxygen to reach
the baby and takes away waste products
·
The
Fetal Period- lasts 7 months, from the 2nd to the 9th month.
o
It
is the longest period.
·
Teratogen- anything that can cause a birth defect
o
4
factors influence the effects of teratogen:
1.) Dose- how much of this teratogen
you receive while pregnant.
·
The
larger the dose, the more harmful it will be to the fetus.
2.) Heredity- The genetic make-up of the mother will
influence the genetics of the baby, and some individuals just have genes that
make them stronger.
3.) Other negative influences- poor nutrition, lack of good
medical care
4.) Age of organism- Teratogens
are most harmful during the embryonic period, because that is when your life
support systems and organs are being developed.
·
Exposure
to these harmful substances risks miscarriage. Prior to implantation, teratogens have little effect.
·
The
damage during the fetal period is minor compared to the embryonic period, but
damage will be to the brain, the eyes, and the genitals.
o
Types
of teratogens:
Prescription Drugs
1.) Thalidomide- sedative given in 1960s, typically in
2.) Diethlstibestrol (DES) -
commonly given from 1940 to 1970 to prevent miscarriages. The daughters of
these women had higher rates of cancer of the vagina, malformed uterus, and in
some cases, had infertility.
3.) Accutane- usually has to be on
birth control when taking this because a pregnancy will result in deformities.
150 documented cases occur a year due to this.
Nonprescription Drugs
1.) Aspirin- linked with low birth
weight babies
2.) Caffeine- could have a miscarriage
or baby could be born being addicted to caffeine and have withdrawal symptoms
3.) Diet pills
Psychoactive Drugs
1.) Alcohol- results in fetal-alcohol syndrome
§
Baby
has facial deformities, defect limbs and heart, below average intelligence, and
mental retardation.