1. Prenatal Development OBJECTIVES You will be able to….
Investigate the 3 periods of prenatal development
Identify and describe the major components of the 3 periods of prenatal development

2. TRIMESTERS
Human gestation or pregnancy lasts about 40 weeks, counting from the first day of your last normal period. The weeks are grouped into three trimesters (TREYE-mess-turs). 1st TRIMESTER= Weeks 1-12 (germinal &embryonic) 2nd TRIMESTER= Weeks (fetal) 3rd TRIMESTER = Weeks 29-40

3. The Germinal Period: The First 14 Days
The zygote travels down the fallopian tube
The zygote duplicates and multiplies
When it grows to about 100 cells it is called a blastocyst
At about a week the 100 cells in the blastocyst separate into two distinct masses
The outer cells become the placenta
The inner cells form a nucleus that will be the embryo

4. ZYGOTE

5. BLASTOCYST

6. The Germinal Period: The First 14 Days
Pregnancy begins at conception (joining of sperm and egg)
When the blastocyst embeds itself into the endometrium of the uterus, implantation has occurred.
The organism will not become an embryo until implantation is successful.
About ½ of all conceptions fail to grow or implant properly and thus do not survive the germinal period

7. IMPLANTATION
Objectives: SWBAT….
Investigate the 3 periods of prenatal development
Identify and describe the major components of the 3 periods of prenatal development

8. The Germinal Period: The First 14 Days

9. The Germinal Period: The First 14 Days

10. The Germinal Period: The First 14 Days

11. Summary: Germinal Period LEFT HAND SIDE
In your own words, summarize what the GERMINAL period means to you.
Objectives: SWBAT….
Investigate the 3 periods of prenatal development
Identify and describe the major components of the 3 periods of prenatal development

12. The Embryonic Period: From the 3rd through 8th week
The formless mass of cells becomes a distinct being
Embryo- the developing human from day 14 – day 56
A thin line ( called the primitive streak) appears down the middle of the embryo
This will become the neural tube at day 22 and will eventually develop into the central nervous system, brain and spinal column

13. Neural Tube

14. Think, Write, Pair, Share LEFT HAND SIDE
Why do you think the central nervous system, brain, and spinal column are the first things to form?
Write answer IN YOUR OWN WORDS pair up and share with partner
Objectives: SWBAT….
Investigate the 3 periods of prenatal development
Identify and describe the major components of the 3 periods of prenatal development

15. Pregnancy Month by Month

16. The Embryonic Period: From the 3rd through 8th week
The head appears the fourth week as eyes, ears, nose and mouth start to form
A tiny blood vessel that will become the heart beings to pulsate around the fourth week
Arm and leg buds emerge around the fifth week
Upper arms, then forearms, palms and webbed fingers grow
Legs, knees, feet and webbed toes can be seen a few days later
Each have the beginning of a skeletal structure
Day the fingers and toes separate

17. The Embryonic Period: From the 3rd through 8th week
The head develops first in a cephalocaudal pattern- Head to Tail
The extremities (arms and legs) grow in a proximodistal pattern- Near to Far
At the end of 8 weeks, embryo weighs about 1 gram and is 1 inch long.
It has all basic organs and body parts (except sex organs)
It’s movements are frequent about 150 times per hour but such movement is random and imperceptible.

19. INTERESTING STUFF! On left hand side
Write down something interesting or surprising that you learned about the EMBRYONIC PERIOD
Objectives: SWBAT….
Investigate the 3 periods of prenatal development
Identify and describe the major components of the 3 periods of prenatal development

20. The Embryonic Period: From the 3rd through 8th week

21. The Embryonic Period: From the 3rd through 8th week

22. The Embryonic Period: From the 3rd through 8th week

23. The Embryonic Period: From the 3rd through 8th week

24. Summary: EMBRYONIC PERIOD on left hand side
Write down IN YOUR OWN WORDS a summary of what the Embryonic Period means to you.
Objectives: SWBAT….
Investigate the 3 periods of prenatal development
Identify and describe the major components of the 3 periods of prenatal development

25. The Fetal Period: From the 9th Week Until Birth
The organism is called a Fetus from the ninth week after conception until birth
If the fetus is a male (XY) the SRY gene triggers the development of male sexual organs, otherwise female organs develop
The male fetus experiences a rush of the hormone testosterone
By the end of the third month, the sex organs are visible via ultrasound (sonogram) which uses sound waves to instead of radiation

26. Formation of the Genitals

27. Male gender With the male fetus, the genital tubercle usually creates an angle of greater than 30° with the lower part of the spine.

28. Female gender In the female fetuses, the genital tubercle protrudes in the same direction as the lower portion of the spine with an angle of less than 30° relative to the backbone.

29. The Fetal Period: From the 9th Week Until Birth
The head of the fetus comprises about half of the total body weight
Facial features appear human in placement and shape by the third month
In the fourth, fifth, and sixth months the heartbeat becomes stronger
Digestive and excretory systems develop
Fingernails, toenails and teeth buds form and hair starts to grow (even eyelashes!)

30. 14 week fetus Ultrasound

31. The Fetal Period: From the 9th Week Until Birth
Age of Viability- When a pre-term newborn can survive outside the womb
22 weeks is the current age of viability- with intensive medical treatment
Even with the most advanced technology, life cannot be maintained without some brain response.
As the brain matures and axons connect, the organs of the body begin to work in harmony

32. Question THINK- WRITE-PAIR-SHARE
22 week is the current age of viability, with
intensive medical treatment…
What do you think a fetus that under developed would need to survive outside the womb?
Objectives: SWBAT….
Investigate the 3 periods of prenatal development
Identify and describe the major components of the 3 periods of prenatal development

33. The Fetal Period: From the 9th Week Until Birth
The brain increases about six times in size
Half a million brain cells are created per minute
Might be the most important and crucial period for brain development
The entire central nervous system becomes responsive during mid-pregnancy (4-6 months)
Basic body functions like breathing, sucking, are regulated

34. The Fetal Period: From the 9th Week Until Birth
Age of Viability –
Only means life outside the womb is possible…
Intensive newborn care is necessary to keep the neonate alive, healthy, and free of disabilities.

35. The Fetal Period: From the 9th Week Until Birth
The last three months of prenatal life, the lungs begin to expand and contract
The fetus begins to exercise breathing muscles by swallowing amniotic fluid as a substitute for air
Heart valves mature
Arteries and veins throughout the body also mature

36. World’s Tiniest Babies http://www. cbsnews. com/2300-204_162-10010544

37. The Fetal Period: From the 9th Week Until Birth
The relationship between the mother and child intensifies during the final three months
The mother’s sounds, tastes for food, and behavior patterns become part of the fetal consciousness
Auditory communication from mother to child begins at the 28th week and improves each week as fetal hearing becomes more acute

38. The Fetal Period: From the 9th Week Until Birth
The fetus startles and kicks at loud noises
Listens to mother’s voice and heartbeat
Is comforted by rhythmic music and movement
If the mother is fearful or anxious, the fetal heart beats faster and body movements increase.

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