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Name _______________________________________
Notes: The Miracle of Life
From Conception to Birth
A. Sex Cells and Chromosomes
1. Sex Cells (also called gametes)
a. Female sex cell – egg cell (ovum)
b. Male sex cell – sperm cell
2. Sex Chromosomes
a. 23 chromosomes in each sex cell
b. 23rd chromosome is the “sex chromosome”
c. Egg cell ALWAYS carries the “X” sex chromosome
d. Sperm cell can carry either the “X” sex chromosome or the “Y” sex chromosome
e. Father determines gender of the child, because they carry both the X and Y chromosomes, while
mothers only carry the X
f. Genetic code for a male baby is XY and female baby is XX
3. Genes
a. Found on chromosomes
b. Pass genetic traits to offspring
4. Inherited Traits
a. Dominant – expressed if one parent has the trait
b. Recessive – expressed only if both parents have the trait
B. Pregnancy
1. Pregnancy
a. Definition: The period of time between conception and birth.
b. Measured in 3 month periods called trimesters and starts from the first day of the last menstrual
period
c. Normally lasts about 9 months or 40 weeks from conception to birth
2. Conception
a. The process of becoming pregnant including fertilization
b. Starts with two tiny cells that join together to grow into a baby
3. Fertilization
a. The strongest, fastest and healthiest sperm have the best chance of fertilizing the egg cell
4. How does a woman know she is pregnant?
a. Missed or late ___________________________
b. _______________________ tenderness or fullness
c. Nausea and sometimes _______________________
d. Changes in ____________________________
e. Frequent ______________________________
f. Tiredness
5. Pregnancy Tests
a. Urine test – HCG
b. Pelvic exam—uterus size
C. Stages of Development
1. Zygote
a. Single cell formed from union of sperm and egg
b. Contains genetic material from both parents
2. From Zygote to Embryo
a. Zygote divides into multi-celled mass called embryo, which
will implant in the uterine lining
b. Embryo searches for a place to implant in the uterine lining or wall
c. It actually burrows beneath the surface
3. From Embryo to Fetus
a. After about two months, the embryo takes on a human appearance and is now called a fetus.
4. Formation o Twins
a. Identical - 1 egg (ovum) is fertilized by 1 sperm which then divides and separates and grows as
two separate embryos
b. Fraternal - 2 eggs are released from the ovary and are fertilized by 2 different sperm
D. Structures inside the Womb
1. Placenta
a. Grows from the outer edges of the embryo
b. Connects embryo to uterine wall
c. Filters nutrients and waste between mother and baby
2. Umbilical Cord
a. Grows between placenta and baby
b. Provides baby with oxygen and nutrients
c. If mother ingests any toxic substances, such as drugs, alcohol or nicotine, the baby receives these
as well
3. How can smoking during pregnancy affect the baby?
In the womb:
a. Low birth ______________________
b. ___________________________ baby
c. Increased risk of birth ____________________
d. ________________________________ birth
After birth:
a. ______________________ and breathing problems
b. Increase risk of ______________________
c. Affect on physical and intellectual ____________________
d. ________________________________ problems
4. Did You Know…?
Pregnant women who use drugs such as heroin, cocaine, marijuana, PCP, methadone, and/or
amphetamines may give birth to drug-addicted babies.
5. How does alcohol use affect the baby?
a. Increased risk of ___________________________________
b. ___________________________ defects
c. Fetal Alcohol Syndrome (__________): facial abnormalities, malformations of the heart, growth
retardation, and mental disorders
6. Amniotic Sac
a. Thin, but strong, membrane filled with fluid that cushions and protects the fetus and regulates its
temperature
E. Labor and Birth
1. Signs of Labor
a. Water breaks: amniotic sac bursts, the fluid is released through the vaginal canal
b. Contractions: uterine muscles give cramping sensation as cervix starts to dilate
c. Either one can happen first. Everyone is different.
2. Birth Positions
a. Normal birth position – head downward in pelvis
b. Breeched birth position – head anywhere else but downward
3. Childbirth
a. Natural birth - baby is pushed through the birth canal (vagina)
b. Caesarian section is the operation performed by the doctor that removes the baby directly from
the uterus by making an incision in the lower abdomen.
c. Cutting and tying of umbilical cord forms the navel
4. First Breath
a. The hole in the heart will close, changing the heart from a
one-pump heart to a two-pump heart.
b. The linking passage outside the heart will close off and force
oxygenated blood to the lungs.
5. Afterbirth
a. Umbilical cord ceases working and is cut and clamped
b. Placenta detaches from the side of the uterus and is pushed
out
__________________________________________________________________________________________
Knowledge Check:
Describe 3 signs/symptoms that a woman may be pregnant.
1. ___________________________________________
2. ___________________________________________
3. ___________________________________________
Describe 2 ways a woman can confirm her pregnancy.
1. ___________________________________________
2. ___________________________________________