Download Chapter 5 Prenatal Development

Chapter 5
Prenatal Development
5-1 The Developing Baby
5-2 A Closer Look at Conception
5-3 Problems in Prenatal Development
5-4 Avoiding Danger to the Baby
The Developing Baby
• Conception
– Ovary releases Ovum (egg)
• 2-3 day journey to uterus – ovum only lives 12 to 24 hours
• Sperm lives for 48 to 72 hours • there are 3 to 4 days in which intercourse could lead to
conception
(Discussion – Why might it be important to know this?)
– Conception occurs when sperm and egg unite
Three Periods
• Zygote - 1st stage (2 weeks of rapid cell division – size of pin head)
– Zygote travels and attaches to uterus for nourishment
• Embryo – 2nd stage (3-8 weeks)
– Major systems of human body form – hearts, lungs, bones, and muscle
with brain taking control of functions.
– Sac of amniotic fluid forms to protect baby.
– Placenta takes food and oxygen from the mother’s blood stream through
umbilical cord to baby.
– The umbilical cord also takes waste away from baby
• Fetus – 3rd stage (9th week to birth) fluid and the woman’s abdomen
continue to grow.
• By the seventh month the fetus is capable of surviving outside the
uterus with medical help as it is in months 8 and 9 that the major
organs mature to function independently and the fetus gains fat
deposits and stores nutrients and build immunities.
• Lightening - In ninth month the baby drops head first into the birth
canal; mother feels more comfortable in her upper abdomen
Group project
• Each group will create a drawing of the baby
at the assigned stage of development and use
labels to highlight the changes that took place
that month. Title drawing with the month.
Copy the following in your journal:
•
•
•
•
What did it feel like walking up the stairs?
Could you touch your toes?
Could you get up off the floor without help?
Write a diary entry in first person as though
you are nine months pregnant. What are you
feeling?
Section 5-2 A Closer Look at
Conception
Discussion:
• Who do you look most like in your family?
• Physical build; skin color; hair texture and
color; shape and color of eyes; shape and size
of hands, ears, and feet; and blood type.
• Musical ability and some medical conditions
may be passed on.
• HOW DOES THIS HAPPEN?
The Chromosome Package
• Chromosome facts:
– Tiny threadlike particles in the nucleus of ever cell
– We have 46 that form 23 pairs (one from momcontributed from the ovum- and one from dadcontributed from the sperm)
– Each chromosome has thousands of genes; these
determine our inherited characteristics
– Two copies of a gene (1 from mom, 1 from dad) create
the inherited characteristic (Dominant gene wins) (Ex.
Blue eyes bb vs. brown eyes BB so Bb =brown eyes)
– Sex chromosomes X and Y; XX = girl; XY = Boy. The sperm
determines the outcome.
• Multiple Births
– Identical Twins – when the fertilized egg begins cell
division and the mass of cells splits in half
– Fraternal twins – mom releases two eggs – result in the
union of different eggs and sperm. (3X’s more)
– The birth of more than two babies may result in either
or a combination
• Infertility – when a couple can’t become pregnant
physical problems may be the cause.
– Fertility drugs may be given to a woman who is not
releasing an egg each month
• Side effects: lung problems, abdominal pain nausea,
diarrhea, or dizziness, and an increased chance of multiple
babies
Options for Infertile Couples
• Adoption
• Artificial Insemination – sperm (husband’s or
donor’s) is injected into a woman’s uterus
• In vitro fertilization - mature egg and sperm are
combined in small dish – zygote is then placed in
uterus to attach to uterus = normal pregnancy
• Surrogate mother – woman who becomes
pregnant for another couple, usually includes
legal arrangement - controversial
Journal assignment
• P. 154 #3 Observing and Participating.
• Make a chart showing the generations of your
family or a family you know from
grandparents through parents and their
brothers and sisters to the present generation
– including brothers, sisters, and cousins. On
the chart show the hair color and eye color of
each person. Write a paragraph describing any
patterns you see.
P
Popa
Nana
Grammy Papa Charlie
(Black/gray, blue, olive) (brown.gray, blue, fair) (brown, blue, olive) (black, blue, fair
Daddy
Mom
(black/gray, blue, olive, square jaw, 6’3)
(brown, blue, olive – died of melanoma 5’5”
Ron Lyndee Sheri Kathy Charles Elenor Betsy Me
Black
6’3
Blue
L. brown
5’6”
blue
L. brown
5’7”
blue
L. brown
5’8”
blue
L. brown
6’4”
blue
L, brown
5’4”
blue
L brown
5’7”
blue
dark b.
5’7”
blue
Section 5-3 Problems in Prenatal
• Losing a Baby (developing baby dies):
– Miscarriage – before 20 weeks
– Stillbirth – after 20 weeks
• Birth Defects – a serious problem that threatens a
child’s health or ability to live.
– 3 out of every 100 children have a birth defect
– 4 main causes: (60 % unknown)
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•
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Environment of developing baby
Abnormal genes
Errors in chromosomes
Combination of Environment and heredity
Causes
• Environmental:
– Nutritional balance of her diet – everything the mother
takes in may affect baby
– Diseases or infections of mother during pregnancy
– Some medicines
– Exposure to outside hazards: radiation
• Hereditary Causes: most imperfect genes we carry are
recessive, but if both parents pass the recessive gene
the child will develop the defect.
– Color blindness and hemophilia affect only males
• Errors in Chromosomes: when a child has too many or
too few chromosomes a defect will occur. In Downs
syndrome has an extra chromosome on pair 21.
• Combination of Heredity and Environment: possible
outcomes- heart defects, clef lip, and spina bifida .
Prevention and Diagnosis
• Genetic Counseling – explains the options and risks. Family
history is taken, medical testing done to determine if there
is a genetic problem and the probability of having a child
with a defect
• Prenatal Testing - many birth defects can be detected, but
no test to see if child is normal
– Blood test
– Ultrasound – sound waves make image of baby
• Developing on schedule
• Skeletal defects and presence or organs
– Amniocentesis – amniotic fluid is drawn and tested
• Most often used to detect Downs syndrome (mom over 35)
– Chorionic villi sampling - ample tests tissue from the membrane
encasing fetus (more risky)
5-4 Avoiding Dangers to the Baby
• Alcohol interferes with tissue growth, brain tissue most
susceptible – child may have fetal alcohol syndrome
(FAS) 1 in 5 die soon after birth. Survivors may be:
– Mentally retarded
– Slow growth,
– Poor coordination
– Heart defects
– Facial disfigurement
– Learning problems & hyperactivity
(Degree of damage is directly related to alcohol consumed
and possibly stage at which she drank)
Other Drugs
• Prescription and Over-the-Counter Drugs
– Medicines or infections during the first three months of pregnancy when body
systems and brain development are most critical can cause retardation
– In last 6 months – slow growth, infections, or bleeding at birth may result
• Caffeine – in small amounts may not harm baby; large amounts may result
in miscarriage, low birth rate, and higher rates of infant deaths
• Tobacco – smaller baby, premature births, respiratory infections and
allergies after birth
• Illegal Drugs – addiction passed on to baby with life long effects.
Withdrawal may result in death, and survivors often cannot understand
school classes. Often these drugs lead to miscarriage, stillbirths, and birth
defects
• X-rays – may cause birth defects
• Rubella – German measles – deafness, blindness, heart disease, mental
retardation
• STD’s – may be passed on to the child, cause deformity and even death.
Syphilis and Gonorrhea may cause blindness – solution placed in babies
eyes at birth to help kill gonorrhea germs
• AIDS – untreated the baby is at risk, mother may be given treatment to
reduce chances her baby will develop it.