1. The Biology of Development I. Pregnancy II. Prenatal Development III. Developmental Hazards

2. I.Pregnancy  How does a person know if she is pregnant?

3. II.Prenatal Development -280 days, 39-40 weeks -3 main periods of Prenatal Development -germinal-embryonic-fetal

4. 1.Germinal Period  1st 2 weeks  Zygote created, cell division  Zygote attaches to wall  Cell differentiation Inner cells (blastocyst) grow into embryo Inner cells (blastocyst) grow into embryo Outer cells (trophoblast) provide nutrients/support for embryo Outer cells (trophoblast) provide nutrients/support for embryo

5. Follicle releasing egg to be fertilzed

6. Zygote

7. Blastocyst

8. Fetal Circulation

9. Embryos

10. 2.Embryonic Period  2- 8 weeks  More cell differentiation  Organogenesis  3rd week--neural tube forms, eyes, ears, nose  24 days--heart cells  4th week-arm/leg buds  6 weeks--hands  8 weeks, primitive heart beating

12. Cell differentiation  Inner cells (endoderm) form internal body parts --digestive/respiratory  Outer cells Ectoderm (outermost)--on surface Ectoderm (outermost)--on surface Form nervous system, sensory, skin partsForm nervous system, sensory, skin parts Mesoderm (middle)--surrounds internal areas, circulatory system, bones, muscles, excretory and reproductive system Mesoderm (middle)--surrounds internal areas, circulatory system, bones, muscles, excretory and reproductive system

13. Life Support Of Embryo 1. Placenta 2. Umbilical cord 3. Amnion

14. Fetal Circulation

15. 3. Fetal Period  Last 7 months  At 3 mos--3 inches long, weighs 1 oz.,  5 mos--lanugo, 11 oz., 10 inches  6 mos.--11-14 inches, 20 oz,  8-9 mos- Proximodistal and cephalocaudal Proximodistal and cephalocaudal

16. III. Developmental Hazards  Teratology…Teratogen 1. Maternal diseases and health AIDS, rubella, syphilis, gonorrhea, polio, diabetes, herpes 2. Age 3. Nutrition 4. RH factor 5. Emotions/Stress 6. Drugs

17. Drugsharmful to Prenatal Development  Thalidomide  Barbituates  Aspirin  Megadoses of vitamins  Alcohol  Nicotine  Caffeine  Narcotics  LSD  Marijuana  Cocaine

18. 6. Environmental hazards  Radiation  Pesticides  PCBs  Mercury  Lead  Toxoplasmosis  Hot temperatures