1. Date: March 20th, 2017- Happy Spring!
Aim # 59: How does an embryo develop inside the uterus?
HW:
Daily Review of class notes.
Test Corrections due Tuesday (must get signed!!)
Castle Learning due Wednesday
Test on Human Reproduction Thursday
Do Now:
What controls the reproductive cycles in males and females?
What is this mechanism called?

2. Aim #59: How does an embryo develop inside the uterus?

3. 1) How long are humans pregnant?
Females are pregnant for nine months or 38 weeks
During this time, the mother and baby undergo many
changes.

4. 2) Embryonic Development:
Fertilization
Mitosis +
Sperm
Egg
Zygote
Embryo- the stage in human development from the
first division of the zygote until about nine weeks
after fertilization.

5. 3) Embryo vs. Fetus Fetus Embryo (8 weeks-Birth)
(Fertilization-8 weeks)
Once the embryo becomes a fetus, all the major
organs have begun to form.

6. Cleavage
The term used to describe the early cell division associated with embryonic development.
During this time period, the number of cells increase tremendously.

7. The result of cleavage is an embryo that is …..
Morula
A solid ball of cells which moves towards the uterus

8. Mitosis continues & the embryo becomes……
Blastocyst
A hollow ball of cells

9. 4) What happens after fertilization?
The embryo travels to the uterus and implants itself in the uterus lining

10. 5) Where does the embryo develop?
In the uterus - womb
Surrounded by an amniotic sac & fluid for protection from shock

11. 6) EARLY DEVELOPMENT
Cleavage occurs by mitosis
4 days the embryo = 50 cells
6-7 days = 100 cells and
attaches to the uterine wall
(IMPLANTATION)

12. Cell division continues & the embryo starts to ….
Gastrula
Fold inwardly

13. Gastrulation Three layers
Each layer will eventually form the different organ systems

14. 7) CELLULAR DIFFERENTIATION
Due to gene expression, cells undergo cellular differentiation, in which the cells become increasingly specialized in structure & function.

15. 8) What does a developing embryo need?
1. Nutrients for ATP & to build its own body parts
2. Oxygen for ATP

16. 9) Embryonic Waste Products
1. Metabolic waste (from cells)
2. Carbon Dioxide

17. a) Umbilical Cord
The umbilical cord is responsible for carrying nutrients and oxygen to the developing fetus, and waste away.

18. b) Placenta The placenta is the organ that allows for the exchange of
nutrients and wastes

19. 11) Fetal Blood Supply
The blood from the baby and the embryo NEVER mix. Materials diffuse between the mother’s blood & the babies blood.

20. 12) Why is the fetus floating in a fluid?
The fetus is surrounded by
amniotic fluid and it helps
absorb shock

21. STRUCTURES BY 3rd WEEK
Placenta
Nervous and endocrine system (starting)
Vital organs forming
Heart is beating

22. FIRST TRIMESTER
Most major organs formed
Umbilical cord formed
Muscular system developed
Reflexes
Amnion formed

23. SECOND TRIMESTER
Tissues become specialized
Skeleton forms
Strong fetal heartbeat
At ~6 months the baby can live outside the mom with life support

24. 3rd Trimester
Fetus doubles in size
Lungs are forming
Sleeps 90-95% of the time
Dreams
Premature if born before 8 months

25. 13) What happens at around 9 months?
The fetus has developed all its
organs and is ready to live in
the outside world
The uterine muscles begin to
contract and the baby is
forced out of the mother.
This process is called:
Labor

26. 14) Prenatal care Good nutrition Moderate exercise No smoking
No drugs, prescription or illegal
No alcohol

27. Fetal Alcohol Syndrome (FAS)
Consuming alcohol during development can cause FAS which has disastrous affects on the CNS.

28. 15) What trimester is the most dangerous?
The first trimester, because all the organs are forming at this time. Dangerous chemicals can affect cell division.