Prenatal stage of development

1. Chapter 4: Prenatal Development and Birth Importance: Hereditary endowment is fixed Favorable conditions in the mother’s body Proportionally greater growth and development takes place Influence of significant people

2. Major Phases of Prenatal Development Scientific term used to describe baby-to-be Major developments in each period

3. I. Germinal Period Period of the Zygote 8-14 days or Weeks 1-2 Conception until implantation

4. Germinal Period

5. Germinal Period

6. Germinal Phase

7. Germinal Phase

8. Germinal Phase

9. Germinal Period

10. Germinal Period

11. Germinal Period

12. Germinal Period

13. Germinal Period

14. Implantation

15. Implantation

16. II. Period of the Embryo When zygote is completely embedded in the uterine wall Body structures and internal organs develop 3 layers begin to form in the embryo: E ctoderm : hair, skin, nervous system Mesoderm: muscles, bones, circulatory system Endoderm: digestive system and lungs

17. Period of the Embryo Embryo rests in a sac called amnion amniotic fluid shock-absorbing protection; constant temperature Chorion : 2 nd membrane after about a month of development; helps form the placenta Weeks 3-8

18. Period of the Embryo 3-week old: salamander 8-week old: most of the organs found in a mature human are in place; visible eyes, jaw, arms and legs About 1 inch long and weighs only a fraction of an ounce

19. Period of the Embryo

20. Period of the Embryo

21. Period of the Embryo

22. Period of the Embryo

23. Period of the Embryo

24. III. Period of the Fetus Weeks 9-38 Much larger and bodily systems begin to work (respiration, digestion, vision) By 22-28 weeks, most systems function well enough that a fetus has a chance to survive age of viability

25. Period of the Fetus Distinct baby-like look May still have trouble breathing and cannot regulate body temperature yet Fetus starts to behave as movements become obvious Begins to hear sounds, taste different flavors

26. Period of the Fetus: 3 rd Month

27. Period of the Fetus: 4 th Month

28. Period of the Fetus: 5 th Month

29. Period of the Fetus: 6 th Month

30. Period of the Fetus: 7 th Month

31. Period of the Fetus: 8 th Month

32. Period of the Fetus: 9 th Month

33. Changes in a pregnant woman’s body