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The Reproductive
Systems
Female Reproductive Structures
§
uterus, endometrium, cervix, fallopian tube, ovaries,
ova, placenta, umbilical cord, amniotic sac
Male Reproductive Structures: testes, penis and sperm
§
Fertilization
The Process of Fertilization
§ Ovulation occurs. Sperm, when present, travel up the
fallopian tube and one may fertilize the egg.
§
The egg changes composition as soon as a sperm penetrates the ovum. When the nuclei
of the male and female cells meld together fertilization has occurred.
Genetics
Chromosomes, DNA, and Fertilization
§
We have 23 pairs of chromosomes
Ø 22 are autosomes
Ø 1 pair is
the sex chromosomes
Ø The chromosome
pairs are a combination of the two parents - unless the egg was cloned.
Ø We normally
get 23 single strands from our mother and another 23 single strands from our father, but as we will see, this may not happen.
PRENATAL DEVELOPMENT
Principles of Prenatal Development
§
Proximodistal
Ø Growth occurs
from the middle to the outside
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Cephalocaudal
Ø Growth occurs
from head (top) to feet (bottom)
§
Mass to specific
Ø Large structures
appear before the finer details
Ø Large movements
occur before finer ones
The three prenatal stages of development:
PRENATAL DEVELOPMENT
The Germinal Stage
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Day 1 to 14
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Not yet attached
PRENATAL DEVELOPMENT
The Embryonic Stage
§
Week 3 to week 8
Week three the heart beats
PRENATAL DEVELOPMENT
The Fetal Stage
Week 9 to birth
Pregnancy
Gestation period = 267 to 277 days
Broken into three equal trimesters of three months each.
There is much variability in the experience of pregnancy.
Let’s look at generalizations:
First Trimester:
Flood of hormones can produce fainting, headaches, weariness,
tender breasts and morning sickness
Miscarriages (spontaneous abortions) are more prevalent
in this trimester.
* 1 in 10 pregnancies end in miscarriages
* With women in their late 30’s, this increases to 1 in 5
Pregnancy
Second Trimester:
Need for maternity clothes
Quickening occurs as baby begins to kick
Attachment begins in earnest
A strong positive attachment predicts positive maternal
bonding after birth
Third Trimester:
Ever increasing physical and emotional issues
Leg cramps, backaches, anxiety, numbness, heartburn,
insomnia
Pregnancy
Emotions and the wider world
The woman’s support group plays a strong role
in the experiences of birth.
Pleasant or unpleasant experience?
Economic factors of the family
The nother's mental health
Availability of health care
Love & Care from those around her (social support)
Fear Factor
Will there be complications or defects?
Ectopic pregnancies occur in 1 out of every 100
Ectopic pregnancies never go to term & can cause
the mother’s death
Ectopic pregnancies must be aborted
Threats to the Developing
Baby
Teratogens – substances that harm the fetus
Some examples of known teratogens:
Medications – Thalidomide
Diseases – Rubella
Drugs – Alcohol, Cocaine
Environment-Pesticides, Radiation
Stress
Threats from Outside
Basic principles
All body parts do not develop at the same time.
Crucial (critical) periods occur for each body part.
In a critical period, it is easier to interfere with
physical development.
Four principles to remember about teratogens:
Teratogens are most apt to cause major structural
damage during the embryonic period.
Teratogens can effect the developing brain throughout
pregnancy.
Teratogens operate in a does-response relationship,
but we do not know where that threshold lies.
Better to be cautious and stay avoid teratogens during
pregnancy
Teratogens may exert their influence long after exposure.
Two Prevalent Teratogens
Smoking
As few as 6 cigarettes a day can cause side effects
and increases the cancer risks in women.
Effects include reduced nutrition and reduced birth
weight
The increase in smoking among women has put newborns
and adult women throughout the world in danger.
Alcohol
Fetal Alcohol Syndrome – the number one preventable
birth defect
How much is too much?
Measurement issues
What should we do?
Should we take 1000 women
and make them drink or smoke during pregnancy? Thatfs not an ethical experiment!
We have to trust self reports; but will a woman give
us the actual
Number of times she drank during pregnancy? Will she
even remember?
Correlational surveys and studies are still being done
in this area to try to find out the exact amount that is safe, but it could be years before we know. In the meantime don’t smoke or drink.
Threats from Within
Genetic and Chromosomal Disorders
We are supposed to have 23 chromosomal pairs, but sometimes
we get an incorrect complement
Too many or too few chromosomes can occur
Down syndrome – trisomy 21
In the past we institutionalized and shorter lives were
expected, but now, with new medical advances and recommendations, a nurturing household has increased life expectancy in people
with Down Syndrome.
Turners syndrome – X
Supermale syndrome XYY
Threats from Within
Mutations on the chromosomes
Chromosomes contain genes with about 50,000 genes per
human cell.
Genes come in pairs – one on each chromosome-
and determine specific traits.
While some traits are dependent on interactions in many
chromosomes, other traits are determined by one chromosome.
In the single allele case (single-gene
disorder), one gene may be dominant and the other may be recessive or dominate.
If
the faulty gene is Sex linked
- it occurs on one of the sex chromosomes. (i.e.Hemophilia)
If the faulty gene
is Autosomalthen it comes in pairs. If the faulty trait is recessive, then it requires both alleles to be recessive for the
trait to occur - called recessive autosomal disorders.
Otherwise, it is a dominant autosomal disorder and only takes one allele.
Hemophilia is a sex linked single gene disease carried
on the X chromosome.
What if the
father has the trait and the mother is a carrier?
Genetic and Chromosomal
Abnormalities
Supermale Syndrome
= Xyy
Kleinfelter's syndrome
= XXy
Fragile X = XY but
the X is broken
Turner's Syndrome
= X
Turner’s syndrome
= X
» There is no
“only” Y - because the X is absolutely required for development to occur
Parkinson
disease = C# 4
Usher & Down
syndromes= C# 21
Alzheimerfs
disease C# 1, 14, 19, and 21.
Cystic Fibrosis = C# 7
Tay-Sachs Disease =
C# 15
Phenylkeptonuria = C# 12
Huntingtonfs
Disease = C# 4
Duchenne muscular
dystrophy = C# X
Tools of Discovery
Sorting out the odds: Genetic Counseling
You can have your genes tested for specific abnormalities.
If you know you and your spouses’ genetic codes,
then a genetic counselor can predict your child’s percentage of getting a disease.
We already saw how this is done in the case of Hemophilia
- a single allele genetic disorder.
Pictures can show gross deformities
Ultrasound technology is commonly used to date the pregnancy
and chart the fetus’s growth, but it can also reveal structural abnormalities.
Tools of Discovery
Tests for genetics:
Testing an embryo prior to birth to see if it has a
faulty genetic code
Amniocentesis
Removal of cells from the amniotic fluid and test the
genetic structure.
Risks:
Miscarriage
Chorionic Villus sampling
Remove villus from the membrane surrounding the fetus
and test its genetic structure.
Risks:
5% risk
of miscarriage
Chance of limb impairment
Contraception/Conception
Humans are not the only animals worried about getting
pregnant. Examples of contraceptive procedures abound in the animal world.
Extended copulation, territoriality, contraceptive plugs
and other devices are used by males of other mammals to assure that theirs is the ONLY possible sperm to produce offspring.
Humans are probably the only animals that copulate and
purposely prevent fertilization of their own sperm (Contraception).
Infertility
When contraceptive procedures are not used, many couples
still are unable to become pregnant.
Infertility is defined as the inability to conceive
a child after a year of unprotected intercourse.
Infertility in the U.S. affects 1 in 6 couples.
It’s a female and a male “problem.”
Infertility can cause grief, despair, a feeling of loss
of control, loss of self esteem, anger and guilt.
Alternate Means of
Conception
Assisted Reproduction Technology Sometimes, when
it is difficult to conceive, science can lend a hand.
BIRTH
Stage 1: Dilation and Effacement
Stage 2: Birth
Stage 3: The Expulsion of the Placenta
Some threats during birth include: baby in breech position,
cervix not fully dilating, difficult position of umbilical cord or placenta.
Birth options:
Natural childbirth
Deliver without medication with the help of midwife
or doula.
Sometimes, medical intervention is needed.
Cesarean
Used a great deal in some countries
Used in the U.S. if complications occur
THE NEWBORN
Tools of Discovery:
Newborn Tests
The Apgar Scale: tests heart rate, muscle tone, respiration,
reflex response, and color.
Threats after Birth
Preterm: born too soon and/or too small
The unthinkable: Infant mortality
Death in the first year of life
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