Parturition/Lactation Flashcards Preview

Reproductive Physiology > Parturition/Lactation > Flashcards

Flashcards in Parturition/Lactation Deck (41):
1

What are the three phases of parturition?

1- initiation of labor 2- delivery of fetus and placenta, 3- uterine contraction to revert back to pregravid size

2

What are the major factors of parturition?

estradiol, PGE2 and PGF2a, and Oxytocin

3

What does PGE2 do in non-pregnant women? pregnant?

relaxes myometrium; uterus contractions (both PGF2a and PGE2

4

What does estradiol do during parturition?

induces PGE2 and PGF2a production in fetal membrane and myometrium and oxytocin receptors in the myometrium

5

What do PGs do during parturition?

initiate uterine contractions, activates stretch receptors in cervixmyometrium (stimulus from fetal head, huge # of stretch and pain fibers in both)

6

What does oxytocin do?

maintains uterine contractions and stimulates PG production

7

What is the mechanism for the onset of labor?

P decreases myometrial contraction during pregnancy, reduced calmoudulin and placental PGE2 synthesis and degradation of PG via PG dehydrogenase; increase E2 near term override P inhibition and stimulate PGE2/PGF2a synth-> uterine contraction and activate cervical collagenase-> soften cervix; 2d half preg. uterus undergoes periodic slow and weak rhythmic contractions (Braxton-Hicks); rate and intensity increases til 2nd phase

8

What causes labor pain?

massive contractions excite uterine pain fibers

9

how does the fetal head assist in onset of labor?

stretches soft cervix-> initiation of neurogenic stimulus to hypothalamus causing oxytocin release-> stimulates placental synth. of contractions->further stretching of cervix-> positive neurogenic feedback loop to oxytocin secretion-> stringer contractions-> leads to fetal exit->10-45 min after delivery ->expulsion of placenta (350mL blood loss)

10

How does estradiol work in mammary gland development?

induces lactotrope hyperplasia, oxytocin receptors in alveolar and ductal myoepithelial cells, stimulates prolactin synthesis; also reduces dopamine synth and D2 receptor level in lactotropes leading to disinhibition of prolactin synth and secretion

11

What hormones are necessary for ductal development?

E2 + GH + prolactin

12

What hormones are needed for lobulo-alveolar development?

P + E2 + Prolactin + GH + Insulin + IGF-I + Thyroxine + Cortisol

13

What role does dopamine play in mammary gland development for lactation?

D from arcuate nucleus fo hypothalamus via D2R activates Gai which inhibits andenylate cyclase activity; Prolactin synth decreases due to low cAMP, secretion decreases due to low intracellular [Ca]

14

What role does prolactin play in galactopoeisis?

stimulates synth of major milk proteins (B-casein 60% and whey 40%-including a-lactoalbumin, b-lactoglobulin, Ig, albumin, and UDP-galactosyl transferase; induces E and prolactin receptors in mammary gland epithelial cells

15

What else is required besides prolactin for galactoporeisis?

cortisol at physiological levels for expression of transcription factors for milk protein synth,

16

Why does galactopoiesis only occur late in gestation even though P is available?

P antagonizes alveolar cells prolactin receptor by inhibiting up regulation of prolactin receptor, reducing estrogen binding, competing for binding of glucocorticoid receptor; high levels of E2 interferes with prolactin binding to its receptors-> inhibits terminal differentiation of alveolar epithelial cells

17

When does breast engorgement and milk secretion occur?

2-4 days postpartum when steroids are sufficiently cleared from maternal blood

18

What stimulus is needed to induce Milk-let-down reflex?

suckling-induced sensory signals from nipple and areola reach SON and PVN-> release of oxytocin-> contractions of myoepithelial cells surrounding ducts and alveoli-> milk flow through the duct (also needed for secretion of prolactin during lactation)

19

What is first milk?

colostrum, high amounts of B-carotene, proteins, IgA, lactoferrin and relatively lower amounts of lactose

20

What is the composition of mature human milk?

Protein 0.8-0.9%, Carb 6.8-7.2%, Fat 3-5%, Mineral 0.2% and water

21

What are the proteins in mature human milk?

B-casein, a-lactalbumin, lactoferrin, IgA, lysozyme, and albumin

22

What are the carbs in mature human milk?

lactose but 30 or more oligosaccharides also present

23

What are the fats in mature human milk?

Triglyc; most common are aplmitic and oleic

24

What are the minerals in mature human milk?

Na, K, Ca, Cl, Mg, P, Fe, Cu, and Zn

25

What does lactoferrin do for the baby?

inhibits growth of iron dependent bacteria in GI tract (coliforms and yeasts requiring iron too)

26

What does secretory IgA do for infant?

protect infant from viruses and B, specifically those that baby, mom and family are exposed to; helps protect against E coli and possibly allergies; other immunoglobins IgG and IgM help protect against B and viral infections

27

What does lysozyme do for the baby?

protects against E. coli and salmonella; promotes growth of healthy intestinal flora and has anti-inflammatory functions

28

What does bifidus factor do for the baby?

supports growth of lactobaccilus-> beneficial B that protects baby against harmful B by creating acidic environment

29

What specifically does suckling induced prolactin do? Suckling induced oxytocin?

stimulates milk synthesis; let down of milk

30

What causes galactopoeisis to cease?

withdrawal of breastfeeding; maintained as long as stimulation of breast is continued

31

What are the advantages of breastfeeding for the infant?

species specificity, optimal growth of infant, breast milk perfectly matches infants daily requirement, long chain FA development; antimicrobial factors protect against illness, prevention of acute illness (diarrhea, necrotizing enterocollitis, meningitis, UTI, and respiratory illness- pneumonia, bronchitis, otitis), protect against chronic illness- juvenile diabetes mellitus and ulcerative colitis; protection against allergic disease, improved cognitive development, reduced risk SIDS, ready source of comfort and security

32

What are the maternal advantages of breastfeeding?

more rapid uterine involution, early return of pre-pregnancy weight, prolonged post-partum anovulation (PRL inhibits GnRH), conectption 1st 6 mo, less menstrual blood loss, cost saving, enhance interaction, convenience and ease of feeding, and reduced risk of : post menopausal hip Fx, pre-menopausal breast cancer, ovarian cancer

33

What are infant contraindications to breast feeding?

prematurity, IUGR and < 6lbs, multiple births, cardiac disease, respiratory distress, infection esp mouth, lactose intolerance, neurologic problem, neonatal jaundice, latch-on problems, reluctant nurses, dysfunctional suckling, and oral anatomic abnormality: cleft lip/palate, micrognathia

34

What are maternal contraindications to breast feeding?

variation in breast appearance (hypoplastic, tubular), excessive or unrelieved postpartum breast engorgement, previous breast surgery or absess, previous problem with milk synthesis, severe or chronic sore nipples: mechanical trauma, yeast or bacterial infection, sensitive/dry skin and consequent skin crack, flat or inverted nipples affecting infant latch on/milk removal, perinatal complication (high bp/infection), underlying systemic illness (cystic fibrosis, diabetes, heart disease), failure of milk production in first 7 days may be sign of Sheehans, or extremes in maternal age (38)

35

What is galactorrhea?

secretion of milky fluid from breast at times other than pregnancy

36

Where can the problem exist in galactorrhea?

activation of afferent neuroendocrine limb, decreased dopamine release or function, prolactinomas of anterior pituitary or ectopi PRL production, elevated TRH during hypothyroidism and chronic renal failure

37

What are examples of activation of afferent neuroendocrine limb in galactorrhea?

stimulation by suckling, excessive manual stimulation, heroes zoster of thoracic nerves, spinal cord lesions and breast surgery

38

What are examples of decreased dopamine release or function causing galactorrhea?

drugs like phenothiazines, morphine, amphetamines, estrogens can interfere with dopamine metabolism

39

What are examples of prolactinemias of anterior pituitary or ectopic PRL production in galactorrhea?

tumors- renal, liver and uterine fibroids

40

What are examples of elevated TRH causing galactorrhea?

in hypothyroid pts sometimes exhibit hyperprolactinemia with remarkable pituitary enlargement due to thryotrope hyperplasia; thyroid replacement with reduction in pituitary enlargement and normalization of PRL

41

What is Sheehan syndrome?

major hemorrhage during postpartum period, can result in ischemia of affected pituitary regions leading to necrosis-> infarction of PRL cells