Fetal development L5

Question 1

How long is the first trimester?

Answer 1

Weeks 1-13

Question 2

What 4 things happens= during week 1-8?

Answer 2

• Fertilization to the end of the 3rd month
• By second week – germ layers form
• Ectoderm, endoderm, and mesoderm
  (gastrulation)
• At one month – size is only 7mm
• Considered fetus after 8th week

Question 3

What 6 things happen during weeks 9-13

Answer 3

• Movement occurs around 9th week
• Heart and brain have formed
• Heart beat by 10th week
• Limb buds with fingers and toes present
• Placenta and umbilical cord develop
• Sucking reflex

Question 4

What is the placenta?

Answer 4

• Temporary organ that connects developing
  fetus to uterine wall - nutrient uptake, waste
  elimination, and gas exchange via mother’s
  blood supply
• Connects to fetus via umbilical cord

Question 5

What blood vessels make up the umbilical cord?

Answer 5

• Contains one vein and two arteries
• Vein carries nutrients and oxygen rich blood to fetus
• two arteries return blood containing waste
  from fetus back to placenta - to mom

Question 6

How long is the second trimester?

Answer 6

Weeks 14-27

Question 7

What 3 things happen during week 17?

Answer 7

By 17 weeks:
* Sucking and swallowing reflexes
* Sex is identifiable
* Skin is bright pink, transparent and covered with soft, downy hair

Question 8

What 3 things happen during week 21?

Answer 8

By 21 weeks:
* Mother begins to feel fetal movement
* Internal organs are maturing
* Eyebrows, eyelids and eyelashes appear

Question 9

What 3 things happen during week 25?

Answer 9

By 25 weeks:
* Eyes open occasionally for short periods of time
* Skin is covered with protective coating called vernix
* Fetus is able to hiccup

Question 10

How long is the third trimester?

Answer 10

Weeks 28-40

Question 11

What 3 things happen during the third trimester?

Answer 11

• Rapid growth
  -fetus is 350 mm – 530 mm long
• Body mass increases from 0.68 kg to 3.4 kg
• Organs are maturing

Question 12

What 4 things happen during week 28?

Answer 12

• If born at this time - considered premature
• Taste buds have developed
• Fat layers are forming
• Skin is still wrinkled and red

Question 13

What 6 things happen during week 32?

Answer 13

• By end of 8 months:
• Tremendous brain growth
• Most body organs fully developed -
  except lungs
• Strong movements visible
• Kidneys are mature
• Skin is less wrinkled
• Fingernails now extend beyond fingertips

Question 14

What 5 things happen during week 36?

Answer 14

• By end of 9 months:
• Respiratory System last to develop
• Digestive System is 2nd last to develop
• Baby now fully developed and can survive
  outside the mother’s body
• Skin is pink and smooth
• Baby settles down lower in abdomen in
  preparation for birth - less active

Question 15

What 5 things happen during parturition (birth)?

Answer 15

• Uterine contractions signal beginning
  of labor
• Cervix thins and begins to dilate
  (max. 10 cm)
• Labor starts when contractions occur every 10-15 min
• Amniotic membrane is forced into birth canal - often bursts during or before delivery (acts as lubrication)
• Contractions start moving baby through birth canal

Question 16

What are 3 birth hormones?

Answer 16

• Relaxin
• Oxytocin
• Prostaglandins

Question 17

What does relaxin do during birth and where does it come from?

Answer 17

Produced by placenta causes
* ligaments in pelvis to loosen - dilates cervix

Question 18

What does oxytocin do during birth and where does it come from?

Answer 18

Hormone from posterior pituitary
* positive feedback loop enhances strength of contractions
* Synthetic oxytocin is sometimes given to start labour

Question 19

What does prostaglandins do during birth and where does it come from?

Answer 19

Released on-site; trigger more contractions

Question 20

What does prolactin do?

Answer 20

Stimulates milk production

Question 21

What does oxytocin do in regards to lactation?

Answer 21

Stimulates milk release from breasts - POSITIVE FEEDBACK