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Chapter 17

Chapter 17. Pregnancy. What do you remember?. Fertilization- union of a sperm cell and egg. This is also called “conception” When a zygote is formed it attaches to the uterine wall. Stays in uterus until birth. So what’s going on?. After about 2 weeks the zygote becomes an embryo.

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Chapter 17

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  1. Chapter 17 Pregnancy

  2. What do you remember? • Fertilization- union of a sperm cell and egg. This is also called “conception” • When a zygote is formed it attaches to the uterine wall. • Stays in uterus until birth.

  3. So what’s going on? • After about 2 weeks the zygote becomes an embryo. • An Embryo is a cluster of cells that develop between the 3rd and 8th week of pregnancy. • The group of developing cells is called an fetus after about 8 weeks.

  4. The Growing Embryo • The cells of an embryo will continue to divide as it grows. Eventually they will form 3 layers of tissue. • 1- respiratory and digestive systems. • 2- muscles, bones, blood vessels, and skin. • 3- nervous system, sense organs, and mouth

  5. Important structures • Amniotic sac- a thin, fluid-filled membrane that surrounds and protects the developing embryo. • Umbilical cord- ropelike structure connecting the fetus with the mother’s placenta. • Placenta- a thick, blood-rich tissue that lines the walls of the uterus and nourishes the embryo.

  6. Stages of Development

  7. Stages of Development

  8. Stages of Development

  9. Multiple births • Result when multiple embryos are formed. • Identical twins- result from a single zygote that splits into two separate embryos with identical traits and the same gender. • Fraternal twins- occur hen two eggs are released and are fertilized by two different sperm. (can be different genders)

  10. Prenatal vitamins provide a balance of calcium, protein, iron, vitamins a, b, and folic acid. • Most women only need about 300 extra calories a day for a healthy weight gain. • Recommended weight gain is 25-35 pounds. Nutrition

  11. Bad nutrition • Not gaining enough can result in a small, undeveloped baby. • Gaining too much weight can result in an early delivery. • Extra weight also increases the mother’s risk of high blood pressure, diabetes, and varicose veins.

  12. Hazards to avoid • Tobacco use • Alcohol use • Drug use • Environmental hazards such as lead, mercury, smog, and radiation.

  13. Complications • Premature birth- born at least 3 weeks before due date. • Miscarriage- spontaneous expulsion of a fetus before the 20th week of pregnancy. • Stillbirth- delivery of a fetus that has died after the 20th week. • Cesarean birth- when an incision is made in the mothers abdomen.

  14. Childbirth: 3 steps • Labor- contractions begin, cervix starts to widen (dilate) • Delivery- baby passes through birth canal. Baby takes it first breath and cries to clear its lungs of amniotic fluid. • Afterbirth- the placenta is still attached to the baby by the umbilical cord. Contractions will continue to push out the placenta.

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