The Miracle of Life From Conception to Birth
Sex Cells (Also called gametes) Egg Cell (or ovum) Sperm Cell
23 chromosomes in each sex cell 23rd chromosome is the “sex chromosome” Sex Chromosomes • Egg cell always carries the “X” sex chromosome • Sperm cell can carry the “X” or the “Y” sex chromosome
Which sex cell determines the sex of the baby?
Genes found on chromosomes pass genetic traitsto offspring
Inherited Traits • Recessive Traits: will be expressed only if both parents carry the trait. • green, blue, hazel grey eyes • blonde, red or straight hair • baldness • attached earlobes • thin lips • near sightedness • color blindness • Dominant Traits: will be expressed if one of the parents has the gene for that trait. • brown eyes • dark, curly or full head of hair • widow’s peak • dimples • freckles • extra digits • double-jointedness
Pregnancy Definition: Period of time between conception and birth measured in three month periods called trimestersstarting from the first day of the last menstrual period normally lasts 9 months or 40 weeks
Conception • Definition: the process of becoming pregnant including fertilization • Starts with two tiny cells (sperm and egg) that join together to grow into a baby
The strongest, fastest healthiest sperm have the best chance of fertilizing the egg Or maybe the most charming… Clip Fertilization
How does a woman know if she is pregnant? Missed period Breast tenderness or fullness Nausea and sometimes vomiting Changes in appetite Urination Tiredness
Pregnancy Tests Urine test – tests for pregnancy hormone, HCG Pelvic exam – checks for enlarged cervix
Zygote Single cell formed at conception by union of sperm and egg Contains genetic material from both parents
Zygote divides into a multi-celled mass called an embryo as it travels down the fallopian tubes From Zygote to Embryo
Implantation of Embryo • Embryo searches for a place to implant in the uterine lining, or endometrium • It actually burrows beneath the surface Actual image of implantation
From Embryo to Fetus EMBRYO FETUS • After about two months, the embryo takes on a human appearance and is now called a fetus. Click the photo to see the first few weeks of development.
Formation of Twins Fraternal Two eggs and two sperm Each have different DNA Identical One egg and one sperm Zygote divides and separates into two Each have the same DNA
Placenta Grows from the outer edges of the embryo Connects embryo to uterine wall Filters nutrients and waste between mother and baby
Umbilical Cord If mother ingests any toxic substances, such as drugs, alcohol or nicotine, the baby receives these as well! Grows between placenta and baby Provides baby with oxygen and nutrients
Amniotic Sac Thin, but strong, membrane filled with fluid that cushions and protects the fetus and regulates its temperature
How can smoking during a pregnancy affect the baby? After birth: • Asthma and breathing problems • Increased risk of SIDS • Affects physical and intellectual growth • Behavioral problems In the womb: Low birth weight Stillborn baby Increased risk of birth defects Premature birth
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.
How does alcohol use affect the baby? • Increased risk of miscarriage • Birth defects • Fetal Alcohol syndrome (FAS) • - facial abnormalities • - malformations of the heart • - growth retardation • - mental disorders
Signs of Labor “Water breaks” - amniotic sac bursts, the fluid is released through the vaginal canal Contractions - uterine muscles give cramping sensation as cervix starts to dilate Either one could happen first!
Birth Natural birth - Baby is pushed out through birth canal (vagina) Caesarian section – Baby is removed from uterus via surgery Click the photo to see how the baby makes its way out of the womb.
First Breath The linking passage outside the heart will close off and force oxygenated blood to the lungs so the baby can take its first breath. The hole in the heart will close, changing the heart from a one-pump heart to a two-pump heart.
Afterbirth Umbilical cord ceases working and is cut and clamped Placenta detaches from the side of the uterus and is pushed out