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Chapter 6

Psychology 2075 Chapter Notes - Chapter 6: Chorionic Villus Sampling, Fetal Alcohol Spectrum Disorder, Congenital Heart Defect

Course Code
PSYCH 2075

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Human Sexuality
Chapter 6
Sperm meets egg: the incredible journey
The egg has no way of movement and is moved by the cilia that lines the
fallopian tubes
A women’s cervix secretes mucus that flushes the passage ways to prepare
for the arrival of the sperm
The sperm travel great distances to reach the vagina and are made up of the
head, mid piece and tail
It is approximately 60 micrometers, and the DNA is found within the nucleus
which is located in the head
The head also contains acrosome (a chemical reservoir) and RNA
The sperm is propelled forward by the flagella this is powered by the
mitochondria found within the tail
Approximately 200 million sperm are ejaculated each time a man
ejaculates this may seem like a lot, but a lot of the sperm are either
deformed, swim up the wrong fallopian tube, or flow out of the vagina due to
Sperm are capable of swimming 1-3 centimeters per hour
Conception occurs in the last third of the fallopian tube
The sperm is attracted to the egg by a chemical secreted by the egg, they
attach to the zona pellucida
The sperm surround the egg and secrete an enzyme called hyaluronidase
o An enzyme secreted by the sperm that allow one sperm to penetrate
the egg by dissolving the Zona Pellucida
Zygote: the developing organism from the time of the union of the sperm and
the egg to about the second week of gestation
36 hours after conception the zygote undergoes rapid cell division, and about
5 to 7 days after conception the mass implants itself in the lining of the
uterus this is where it nourishes and grows
The cell mas is called an embryo from week two to week eight and from the
on its is called a fetus
Improving the chances of conception: making a baby
Conception is at its highest chance when the women is ovulating this tends
to be 14 days after menstruation
A way to know if a women is ovulating is to take her basal temperature (right
when she wakes up before she starts her day, when she has a spike in
temperature you know that’s he will be ovulating), another way is by taking
an ovulation test

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It is best to have sex 4 time the week the women is ovulating, allowing the
sperm to regenerate (allowing a build up off 200 million sperm)
It is best to have the women lying on her back so that the sperm does not
flow out after ejaculation (best if she stays in this position for about half an
hour to an hour)
Lubrication should not be used as it can block the entrance to the uterus
Development of the Conceptus
In the past the relationship between the mother and the baby has been
described as a harmonious co-existence
But diseases like gestational diabetes, which is just like diabetes except
occurs during pregnancy and pre-eclampsia where the women has a high
spike in blood pressure, protein in the urine and swollen feet hands in the
third trimester
Pregnancy last about 9 months and is divided into three trimesters
(trimester 1 month 1-3. Trimester 2 month 4-6 and the third 7-9)
The Embryo and its Support system
During the first eight weeks of development, the major organ systems are
developed with amazing speed
The mass of cells divided into the ectoderm and endoderm, later the
mesoderm is developed between the two
The ectoderm will create the nervous system and the skin, the endoderm will
differentiate into the digestive system from the pharynx to the stomach
intestines, the rectum and the respiratory system
The muscles the skeleton, connective tissues, and reproductive and
circulatory system derive from the mesoderm
The body of the baby develops head to feet, this is why the embryo has a very
Placenta: an organ formed on the wall of the uterus through which the fetus
receives oxygen and nutrients and gets rid of waste products
The placenta is the place where the mothers blood and nutrients are
exchanged with the baby
They are connected by the tendrils that penetrate the wall of the blood
vessels in the uterus
It is important to remember that the mothers and the fetus’s circulatory
systems are completely separate from one another
The fetus’s blood passes out of the body through the umbilical cord which is
connected to the placenta
The blood of the fetus passes through the villa found in the placenta, and the
mothers passes on the outside of these vessels, creating a membrane
The membrane is permeable to some molecules and nutrients like oxygen
It is also permeable to some drugs so the mother has to be careful of what
she takes
Carbon dioxide and waste is passes out of the fetus and into the mother

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Some disease can pass through the membrane syphilis
But the mother may have a terrible cold and the baby could be perfectly
Another major function of the placenta is to produce estrogen and
progesterone physical symptoms of pregnancy may be caused by these
elevated levels
The placenta also produces Human Chorionic Gonadotropin (hCG)
o A hormone secreted by the placenta, it is the hormone detected in
pregnancy tests
Umbilical Cord: the tube that connects the fetus and the placenta
o Can be around 20 inches long and contains two main arteries and one
Two membranes surround the baby: the amnion and the Chorion
The amnion is the inner most layer and is filled with amniotic fluid
o The watery fluid surrounding the fetus in the uterus, serves as
protection for the baby
Fetal Development
The fetus is mostly developed in the first trimester: it resembles a small
human being and contains all the vital organs
Through the rest of the pregnancy it is mostly enlargement and
differentiation of the different structures
Table 6.1 in the text book
During the seventh month of pregnancy the fetus turns to assume a head
down position
The stages of Pregnancy
The first trimester:
o Women experience many different symptoms of pregnancy, some may
experience nausea, tender breasts, tingling sensation in the nipples
o A tell tale sign is a missed menstrual period
Not always the case, some women may randomly skip there
period, or stress and disease can delay it
o A women should know she is pregnant as soon as possible so that she
can get the ore natal care that she needs, or if she does not want to
carry the baby to term needs to know because it is much safer and
simpler in the first trimester
o Pregnancy tests are 99 percent affective (done in a laboratory)
o Immunologic tests are done by the detection of hCG
o Home pregnancy tests are not very reliable, they produce false
negatives (10/18 women) and also have a 16 percent rate of false
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