Chap 3 prenatal development

Question 1

identify prenatal development stages and discuss milestones in eac

Answer 1

chap 3 objective #1

Question 2

Discuss common agents that cause defects in the developing embryo

Answer 2

chap 3 objective #2

Question 3

• Gestational Age

- Trimester System

Answer 3

Prenatal classification system

Question 4

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

Answer 4

Gestational Age

Question 5

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

Answer 5

Trimester system

Question 6

• Period of the Zygote
• Period of the Embryo
• Period of the Fetus

Answer 6

3 prenatal periods

Question 7

• lasts approximately 2 weeks

- From time of conception to zygote implanted into the uterus

Answer 7

Zygote period

Question 8

• extends to the end of 8 weeks past conception

- All major body structures formed

Answer 8

Embryo period

Question 9

Extensive growth and refinement of body structures: “growth and finishing”

Answer 9

Fetus period

Question 10

Most important prenatal period

Answer 10

Embryo period*

important per Dr W.

Question 11

Trimester 1
Trimester 2
Trimester 3

Answer 11

Milestones of Prenatal development

Question 12

• this is an organism containing 48

- chromosomes and typically not susceptible to teratogens

Answer 12

Zygote

Question 13

• the zygote is implanted into the uterus

- teratogens can be harmful

Answer 13

Embryo

Question 14

Embryo divides into 3 layers

Answer 14

• ectoderm
• Mesoderm
• Endoderm

Question 15

nervous system in the skin

Answer 15

ectoderm

Question 16

muscle, skeletal, circulatory, organs

Answer 16

Mesoderm

Question 17

digestive (immunity) , lungs, urinary tracts

Answer 17

Endoderm

Question 18

Weeks 3 through Week 8

Answer 18

period of the embryo

Question 19

Ectoderm folds over to form the neural tube

*becomes the spinal cord and brain

Answer 19

Week 3

Question 20

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

Answer 20

Week 4

Question 21

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

Answer 21

Week 5 and 6

Question 22

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

Answer 22

Week 7 and 8

Question 23

Weeks 9 through Weeks 32 or more

Answer 23

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

Question 24

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

Answer 24

Week 13 through 16

Question 25

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

Answer 25

Week 17 through 20

Question 26

this allows fetus to maintain body heat

Answer 26

Brown-fat

Question 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

Answer 27

Week 21 through 25

Question 28

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

Answer 28

Week 23

Question 29

Age of viability

Answer 29

22 to 26 weeks

Question 30

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

Answer 30

Week 26 through 29

Question 31

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

Answer 31

week 30 though 34

Question 32

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

Answer 32

Week 35 through 38

Question 33

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

Answer 33

Closure of ductus arteriosus

Question 34

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

Answer 34

Closure of foramen ovale