Chap 3 prenatal development Flashcards Preview

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Flashcards in Chap 3 prenatal development Deck (34):
1

identify prenatal development stages and discuss milestones in eac

chap 3 objective #1

2

Discuss common agents that cause defects in the developing embryo

chap 3 objective #2

3

-Gestational Age
-Trimester System

Prenatal classification system

4

-Measured in weeks
-From 1st day of last menstrual period
-From moment of conception (in vitro )

Gestational Age

5

-arguments against this method
-40 weeks (or even 38) is not divisible by 3
-Not precise enough
-still use though

Trimester system

6

-Period of the Zygote
-Period of the Embryo
-Period of the Fetus

3 prenatal periods

7

-lasts approximately 2 weeks
-From time of conception to zygote implanted into the uterus

Zygote period

8

-extends to the end of 8 weeks past conception
-All major body structures formed

Embryo period

9

Extensive growth and refinement of body structures: "growth and finishing"

Fetus period

10

Most important prenatal period

****Embryo period*****
important per Dr W.

11

Trimester 1
Trimester 2
Trimester 3

Milestones of Prenatal development

12

-this is an organism containing 48
-chromosomes and typically not susceptible to teratogens

Zygote

13

-the zygote is implanted into the uterus
-teratogens can be harmful

Embryo

14

Embryo divides into 3 layers

-ectoderm
-Mesoderm
-Endoderm

15

nervous system in the skin

ectoderm

16

muscle, skeletal, circulatory, organs

Mesoderm

17

digestive (immunity) , lungs, urinary tracts

Endoderm

18

Weeks 3 through Week 8

period of the embryo

19

Ectoderm folds over to form the neural tube
*becomes the spinal cord and brain

Week 3

20

-Neural tube becomes thicker and begins to close, producing the spinal core
-limbs develop in a proximodistal fashion

Week 4

21

-placental circulation occurs via the umbilical cord
-continued differentiation of the brain (maturation)
-stomach and intestines continue to grow and change position

Week 5 and 6

22

-Ossification
-heart will have primitive arteries
-head is forming more and body is curled

Week 7 and 8

23

Weeks 9 through Weeks 32 or more

-Head continues to grow faster than body
-sex becomes visible
-Digestion system begin to function
-improved vascularization occurs
-heartbeat can be heard the stethoscope

24

-Body becomes more proportional
-coordination improves
-ossification stays active
-reflexes strengthen

Week 13 through 16

25

-feel movement
-adipose tissue and brown fat develops
-continued lung maturation

Week 17 through 20

26

this allows fetus to maintain body heat

Brown-fat

27

-increased survival rate
-increased weight gain
-enhanced lung development
-surfactant- develops
-by the end taste buds appear
-eyelids are completely formed and eyelids open

Week 21 through 25

28

what week can the fetuses be born and still survive with intensive life support

Week 23

29

Age of viability

22 to 26 weeks

30

-increased weight gain
-fat accumulation
-still has immature thermal regulation
-neonatal reflexes are fully developed
-head hair appears

Week 26 through 29

31

-continued weight gain
-still require thermal support if born between 30-32 weeks: survival chances much higher

week 30 though 34

32

-additional weight gain (up to 2lbs)
-Fetal movement may begin to decrease

Week 35 through 38

33

at birth
-Passageway between pulmonary trunk and aorta (allows for bypass of the lungs)
-typically closes spontaneously

Closure of ductus arteriosus

34

at birth
-passageway between the right and left atrium
-Closes within first 3 months

Closure of foramen ovale