Human Sexuality Midterm 2
Chapter 6 Conception, Pregnancy, and Childbirth
Ovulation occurs on approximately the 14 day of the menstrual cycle.
The egg is released from the ovary into the body cavity, then picked up by
fimbriae (finger structures at ends of fallopian tubes) and enters the tube.
In about 5 days, the egg reaches the uterus if it has been fertilized.
The cervix secretes mucus to flush the passageways for the arrival of the sperm.
Sperm are produced in the seminiferous tubules of the testes, collected and stored
in the epididymis. During ejaculation, they are moved up and over the bladder in
the vas deferens, and then travelled through the ejaculatory duct through the
The sperm has three body segments.
o The head of the sperm contains the DNA, RNA for early embryonic
development, and a chemical reservoir called the acrosome.
o The middle piece contains mitochondria, which provide energy.
o The tail is what propels the sperm forward it utilizes the energy produced
by the mitochondria and lashes it’s tail back and forth.
Typical volume of ejaculate is 3mL, containing 200 million sperm.
Sperm are capable of swimming 13 cm per hour. It is thought that uterine
contractions may help speed them along.
Of the original 200 million, only about 2,000 will reach the tube containing the
egg chemicals secreted by the egg attract the sperm as they draw closer.
The egg is surrounded by a gelatinous layer called the zona pellucida sperm
secrete an enzyme called hyaluronidase (produced by the acrosome) which
dissolves the zona.
Once fertilized, the zygote travels down the fallopian tube. After 36 hours, cell
division begins. Zygote = first two weeks, weeks 28 = embryo, week 8birth =
Development of Fetus
For 38 weeks, two organisms, the mother and the fetus, coexist.
Both fetus and mother need a variety of nutrients, and may be competing for
them. For this reason, the relationship is no longer viewed as harmonious.
Gestational diabetes woman has high blood sugar because the body is not able to
make all the insulin it needs.
Preeclampsia occurs during the third trimester, sharp rise in blood pressure,
presence of protein in blood, and swelling of hands, feet, and face.
The Embryo and its Support System
After finally arriving the uterus, it implants itself in the uterine wall.
Tendrils form the zygote begin to penetrate the blood vessels in the wall of the
During the first 8 weeks (embryonic period), most of the major organ systems are
formed. Human Sexuality Midterm 2
The cells differentiate into two initial layers, and later a third layer forms between
the two initial ones.
o Ectoderm forms the entire nervous system and the skin.
o Endoderm differentiates into the digestive system, and the respiratory
o Mesoderm muscles, skeleton, connective tissues, reproductive and
Another group of cells, called Trophoblasts, becomes the placenta. It nurtures
growth by producing tendrils that penetrate the walls of the uterus. The placenta
serves as a site for the exchange of substances between the woman’s blood and
The placenta creates a barrier between the fetus’ blood as it passes through the
umbilical cord. There it circulates in the numerus villi some substances can pass
through the barrier, like oxygen and nutrients, while others can’t.
The placenta secretes hormone produces large quantities of estrogen and
progesterone. Another hormone that is produced is hCG (human chorionic
gonadotropn). hCG is the hormone that is dthected in pregnancy tests.
The umbilical cord forms during the 5 week of embryonic development a full
one is 20 inches long.
Two membranes surround the fetus chorion and the amnion. The amnion is the
innermost membrane, and it is filled with fluid that cushions the fetus and
maintains its temperature.
The stages of Pregnancy
The first sign of pregnancy is a missed menstrual period. However, some women
experience some cyclic bleeding or spotting throughout the term.
Increased body temperature due to level of progesterone manufactured by the
Tenderness of the breasts, and sensitivity of the nipples nausea and vomiting.
Frequent urination and feelings of fatigue.
The common pregnancy test is based on detecting the presence of hCG (human
chorionic gonadotropin secreted by the placenta) found in urine. 98% accurate
seven days after implantation.
BetahCG radioimmunoassay is a blood test that detects the same hormone. It’s
more effective can detect lower levels, but it is more expensive.
Physical changes include large increase in levels of hormones (estrogen &
progesterone). The pH level of the vagina change so discharge may increase.
Fatigue and sleepiness are affects of the high levels of progesterone.
Woman becomes aware of fetus’s movement and aware of her size.
Many of the physical symptoms in the first trimester disappear and discomforts
are at a minimum.
Constipation, nosebleeds, and edema are new problems that occur.
Psychologically, the woman is usually relatively calm and well. Depression is less
likely if her partner/spouse live together. Human Sexuality Midterm 2
Uterus is large and hard size of it puts pressure on other organs, causing some
The average weight gain during a pregnancy is between 1540 lbs. The average
full term infant at birth weighs 7.9 lbs, so the rest of the weight is accounted for
by the placenta (1lb), amniotic fluid (2lbs), enlargement of uterus & breasts
(3.5lbs), and additional fat.
The uterus tightens occasionally (not part of labour) but strengthens uterine
muscles. These are called BraxtonHicks contractions.
Lightening/dropping/engagement head of the fetus drops into the pelvis.
Psychological wellbeing is greater among women who have social support, higher
incomes, and experience fewer concurrent stressful life events.
Intercourse can continue safely until four weeks before the baby is due.
The Father’s experience in Pregnancy
Some men experience physical symptoms indigestion, gastritis, nausea, and
change in appetite, headaches. This is called Couvades syndrome, brought on by
hormonal changes in the male.
Lower levels of testosterone may facilitate paternal behaviour.
Nutrition During Pregnancy
Mother needs more energy, protein, vitamins, and minerals.
Overweight and obese women are at increased risk of negative outcomes for both
themselves and fetus.
o Mother Hypertension, gestational diabetes, and caesarian delivery.
o Fetus spina bifida, cleft palate, hydrocephaly.
Protein is important for building new tissues.
Folic acid is important for growth deficiency can cause anemia and fatigue.
The mother needs to intake more iron, as the fetus draws off iron for itself from
the blood that circulates into placenta.
Calcium is needed to prevent muscle cramps, nerve pains, uterine ligament pains,
sleeplessness, and irritability. As well as increased blood pressure.
Substances Causing Birth Defects
Teratogens: Any substance that produces defects in fetus.
Alcohol because alcohol can pass through the membrane barrier in the placenta,
maternal drinking can have pervasive effects on fetal growth and development.
Fetal alcohol spectrum disorder all outcomes associated with any amount of
alcohol exposure during pregnancy .
Dosedependant the more alcohol the mother drinks, the larger the number
and severity of effects on the chil