Reproduction 4

Question 1

Why does blood bypass the fetal lungs?

Answer 1

Because it is not functional yet, and we don’t want to send blood their - only some of the blood is transported to the lungs and liver bc they still need blood to develop

Question 2

How can blood bypass the fetal lungs?
What are the 3 vascular shunts?

Answer 2

Ductus venosus: venous shunt bypassing the liver (-> It can be dangerous if the mother takes drugs bc the fetus liver doesn’t work yet -> drugs get captured in the fetus circulation)

-Foramen ovale: opening between the atria to bypass pulmonary circulation -> blood goes from right atria direct to left atria and bypasses the lungs

-Ductus arteriosus: transfer blood from right ventricle to the aorta -> pulmonary circulation bypassed

Question 3

What are teratogens?

Answer 3

-cause congenital malformations during embryonic development
-depends also on the stage of pregnancy -> more sensible in the early stages

Question 4

What are the hormonal changes during pregnancy?

Answer 4

1. secretion of hCG by thromboblast -> to maintain corpus luteum
2. corpus luteum secretes estrogen and progesterone
3. later placenta will produce estrogen and progesterone by its self

Question 5

RECAP: Functions of estrogen and progesterone:

Answer 5

-inhibit secretion of FSH and LH
-stimulate and maintain uterine lining (proliferative and secretory)
-aid in breast development
-estrogen upregulates oxytocin receptors in uterus myometrium to stimulate contraction -> permissive effect (one hormone upregulates receptor of another hormone)

Question 6

What can cause depression during pregnancy?

Answer 6

A huge drop of estrogen after childbirth

Question 7

What can cause morning sickness during pregnancy?

Answer 7

Peak of hCG

Question 8

More hormonal changes during pregnancy:

Answer 8

-placental lactogen: stimulates breast development
-prolactin: increases breast development and milk production
-aldosterone: water and sodium retention
-insulin sensitivity decreased: gestational diabetes mellitus
-cortisol: increases body fat and appetite + lung development of the fetus (targets type 2 cells to secrete surfactants)

Question 9

Process of the childbirth:

Answer 9

1. Fetus’s head pushes and stretches the Cervix
2. positive feedback to an action potential in Hypothalamus
3. Secretion of Oxytocin by the posterior pituitary (storing oxytocin)
4. Oxytocin causes more contraction of the uterus -> stretch of cervix
   + 5. Positive feedback from stretched cervix -> causes more contraction of uterus
   and positive feedback from prostaglandin (local) causing contraction of the uterus

Question 10

What is the consequence of the positive feedback to more uterus contraction?

Answer 10

The contraction becomes longer, and there is less time in between

Question 11

Terms of the breast anatomy (surface):

Answer 11

Nipple and Areola

Question 12

How are mammary glands developed to produce milk during pregnancy?

Answer 12

Breast development is stimulated by estrogen, progesterone, placental lactogen, and prolactin

Question 13

What happens inside the mammary glands?

Answer 13

-Little alveoli grow and acquire lumen in mid-pregnancy

-smooth muscles respond to Oxytocin and push the milk out into the ducts and out of the nipple the smooth muscles

Question 14

What is Lactation?

Answer 14

-Colostrum: released in the first 2-3 days -> rich in vitamin A, protein, minerals, and antibodies (not rich in calories)

-followed by real milk production mediated by prolactin
-milk let-down mediated by oxytocin

-> production of prolactin and oxytocin (also when baby cries) are stimulated by the suckling of the baby (mechanoreceptors in the nipple)

Question 15

What is also caused by prolactin?

Answer 15

inhibits the cycling to some degree -> by inhibiting FSH and LH, reduces fertilitiy

Question 16

Where is Prolactin secreted from?

Answer 16

Anterior pituitary

1. Suckling of the baby
2. Mechanoreceptors in nipple respond
3. Decrease of Dopamine = inhibiting factor for prolactin -> release of prolactin from anterior pituitary
4. Milk synthesis

Question 17

Where is Oxytocin secreted from?

Answer 17

From the posterior pituitary

1. Suckling of the baby or other stimuli
2. Mechanoreceptors in nipple respond
3. Posterior pituitary releases Oxytocin
4. Contraction of myoepithelial cells -> Milk ejection

Question 18

What happens to the shunts that prevented blood flow to the developing lung and liver?

Answer 18

Umbilical arteries and vein constrict and
become fibrosed -> fibroses becomes a solid ligament (reparative response)

– The ductus venosus (bypassed the liver) becomes the ligamentum venosum
– The foramen ovale (right atrium to left atrium) becomes the fossa ovalis
– The ductus arteriosus becomes the ligamentum arteriosum (bypassed pulmonary circulation - right ventricle -> aorta)