Transcript The Life Cycle

The Life Cycle
• Your Life Began as a Single cell, smaller than this
period at the end of this sentence .
• Now your body is made up of trillion of cells, forming
the organs, and tissues in your body!!
•This microscopic cell formed by the union of an egg cell
(Ovum), from the Female and a Sperm cell from the Male.
This is called FERTILIZATION. Also known as
CONCEPTION.
•The resulting cell is now called a Zygote.
How it all starts……..
Each woman is born with two ovaries that
are positioned in her pelvis. These ovalshaped organs produce one egg per month
in response to the woman’s monthly cycle
of hormones. Generally, one ovary produces
one egg one month and the other ovary
produces an egg the next month.
Implantation is when the Zygote attaches to the Uterine Wall.
• The Cluster of cells that was once called a
Zygote is now called an Embryo during the
third and eight weeks of pregnancy.
• From the eighth week of pregnancy until
term , the developing cluster of cells is
called the Fetus.
Zygote
Embryo
9 weeks
Fetus
Embryonic Growth
As the embryo continues to divide , it forms 3 tissue layers that later
become Various body systems.
• 1st layer becomes the Respiratory and
Digestive system.
• 2nd Layer develops into Muscle, Bones,
blood vessels, and skin.
• 3rd layer forms the nervous system, sense
organs, and mouth.
Amniotic Sac is a thin, fluid- filled
membrane that surrounds and protects the
developing embryo.
1st- Dilation
2nd- “Crowning” passing through
the birth canal
3rd- Afterbirth
Placenta is a thick-rich tissue that lines the walls of the Uterus
during pregnancy and nourishes the embryo.
Umbilical
Cord
A rope like structure that connects the embryo and
the mother’s Placenta.
Fetal Development
• 9 months/ 3 month
periods called
TRIMESTERS
• Pg. 488 Figure 19.2
• Review Trimesters
Identical twins result when a single egg has
been fertilized by one sperm, it divides and
forms two embryos. Being that they
originated form the same zygote, identical
twins have the same genetic make-up.
Fraternal twins form when the ovaries
release two egg’s. Therefore two sperm
fertilize each egg and two embryos develop.
The genetic make-up is different
Tobacco, alcohol, and other drugs used by the mother can enter
the body of the developing fetus and have harmful effects.
Tobacco and Pregnancy
•It is estimated that smoking accounts for up to ;
30 % of low birth weight babies
14% of premature births
10% of all infant deaths.
•Pregnant females repeatedly exposed to secondhand smoke also
have increased of have low birth weight babies!
Any Alcohol consumed during pregnancy quickly passes through
the umbilical cord to the Fetus.
A group pf alcohol-related birth defects that includes both
physical & mental problems. Life Consequences:
•
Mental retardation, learning disabilities
•
Serious behavior problems, slowed growth
•
Physical deformities; including a small skull, abnormal
facial features, heart defects.
Common Physical effects of FAS
Medicines,other drugs, and Pregnancy
• Serious consequences using drugs, even over-the counter
medicine are:
-weakened mother’s immune system, resulting in
improper care of the baby.
-Hinder fetal development
-birth defects,premature labor, miscarriage
-The baby can be born addicted to the drugs the
mother uses during pregnancy, causing the baby to go
through withdrawl after birth.
Environmental Hazards
Harm to the Fetus can result when the mother is exposed
to some common substances in the environment
1.
2.
3.
4.
Lead-exposure has been linked to miscarriages,low birth
weight,mental disabilities & behavior problems in
children.
Smog- air pollution has been linked to birth defects, low
birth weight,premature birth, stillbirths, & infant death.
Greatest risk is during the second month when most
organs & facial features develop.
Radiation- Ionizing Radiaiton-type found in X-rays, can
affect fetal growth & cause mental retardation.
Cat Litter- Contains parasites that cause a disease that
can result in miscarriage,premature labor,and health
problems in newborns.
1. Miscarriage = spontaneous expulsion of a fetus that
occurs before the 20th week of a pregnancy.
A dead fetus expelled from the body after the twentieth week
is called a Stillbirth.
2. Ectopic pregnancy = pregnancies result when the zygote
implants in the fallopian tube, the abdomen, the ovary,or the
cervix.
This can occur when the fertilized egg can’t pass to the uterus,
sometimes b/c of inflammation or scar tissue that has developed as
a result of a Sexual transmitted disease.
3. Preeclampsia = also called, toxmia, can prevent the placenta from
getting enough blood, This may result in low birth weight and problems
for the mother; such as high blood pressure, & swelling.
4. Gestational Diabetes = Gestational diabetes affects about 4% of
all pregnant women . Gestational diabetes starts when your body is
not able to make and use all the insulin it needs for pregnancy.
Without enough insulin, glucose cannot leave the blood and be
changed to energy. Glucose builds up in the blood to high levels.
This is called hyperglycemia.