1. Chapter 18: Growth and Development

2. Embryonic development
fertilization: the fusion of male and female gametes to form a zygote.

3. Once the egg joins with the sperm, it makes a zygote and then begins to divide
The zygote now goes through MITOSIS as it travels down the fallopian tubes on its way to the uterus

4. This mitotic cell division of the zygote is called cleavage

5. Process of cleavage
The zygote divides by mitosis into 2 identical cells
These 2 cells divide into 4 cells

6. Those 4 divide into 8 cells
Those 8 divide into 16 cells and forms a solid ball of cells called the morula

7. As the cells continue to divide, the center of the ball becomes hollow
This hollow ball stage is called the blastula

8. By the end of the six days the zygote is called a blastocyst

11. The blastula stage is followed by the formation of the gastrula
During the formation of the gastrula, one side of the blastula pushes inward to form the 3 germ layers

12. The 3 germ Layers
This results in the formation of a second inner layer of cells called the endoderm
The outer cell layer is called the ectoderm
A third cell layer forms between called the mesoderm

13. The gastrula will eventually differentiate to form the specialized cells.
Differentiation means that the cells will develop specific jobs and develop into specific tissues in the maturing organism.

14. In an embryo, the formation of many types of tissues and organs occur as a result of differentiation

15. After the 3 germ layers have formed, the nervous system begins to develop
The ectoderm cells along the back of the embryo begin to grow into a long hollow tube called the neural tube

16. The neural tube becomes wider at one end
The wider part develops into the brain
The long and narrow end develops into the spinal cord

17. There are 2 main groups of cells in the blastocyst
1. one group will become the embryo
2.The outer layer of cells is called the trophoblast

18. Functions of the trophoblast
Once inside the uterus it attaches to the uterus lining
It secretes the hormone HCG which tell the corpus luteum to keep making progesterone so that menstruation will stop

19. it’s the layer of cells around the embryo that connects the embryo to the lining of the uterus[implantation]

21. After implantation, a membrane on the outside called the chorion forms
It connects to the uterine wall

22. A membrane on the inside called the amnion forms the amniotic sac
The amniotic sac contains the amniotic fluid that surrounds and protects the embryo

23. What is the purpose of the amniotic fluid?
it helps keep the baby warm
provides lubrication that keeps body parts from growing together
helps the baby's lungs develop
lets the baby move easily so he can exercise his muscles and strengthen his bones before he’s born.
it acts like a liquid shock absorber for the baby by distributing any force that may push on the mother’s uterus

24. The chorion begins to grow into the mother’s tissue
Blood vessels develop in this fetal tissue

25. At the same time, tissue with its own blood vessel grow from the uterine lining of the mother, this structure is called the placenta

29. What is the function of the placenta?
Allows nutrients and oxygen to diffuse from the mother to the baby
It also helps to protect the baby from infections because it keeps the mother's blood and baby's blood separate by acting as a filter

30. The umbilical cord connects the placenta to the baby

31. Danger signs during pregnancy

32. Assisted reproductive technology methods
Test to detect birth defects during pregnancy
Stages of labor and childbirth
Pain relief during childbirth

33. Stages of a developing baby
Stage 1: zygote day 1 – day 7
Stage 2 embryo day 8 – week 8
Stage 3 fetus week 9 – week 40

36. 4 stages of the human life cycle
1. Infancy/toddler
2. childhood
3. adolescence/teenager
4. adulthood

37. https://youtu.be/J5TJfZUAETA