Placental Hormones Flashcards
Human chorionic gonadotropin (hCG)
- Maintains the corpus luteum of pregnancy
- Stimulates secretion of testosterone by developing testes in XY
embryos
Estrogen
- also secreted by the corpus luteum of pregnancy
- Stimulates growth of the myometrium, increasing uterine
strength for parturition
Progesterone
- Also secreted by corpus luteum of pregnancy
- Suppresses uterine contractions to provide quiet environment
for the fetus - Promotes formation of a cervical mucus plug to prevent uterine
contamination - Helps prepare the mammary glands for lactation
Human chorionic somatomammotropin
- has a structure similar to that of both growth hormone and
prolactin - reduces maternal use of glucose and promotes the breakdown of stored fat (similar to growth hormone) so that greater quantities of glucose and free fatty acids may be shunted to the fetus
- Helps prepare the mammary glands for lactation ( similar to
prolactin)
relaxin
- also secreted by the corpus luteum of pregnancy
- Softens the cervix in prep for cervical dilation at parturition
- Loosens the connective tissue between the pelvic bones in prep
for parturition
placental PTHrp
- Parathyroid hormone-related peptide
- Increases maternal plasma Ca2+ level for use in calcifying fetal
bones - if necessary, promotes localized dissolution of maternal
bones, mobilizing their Ca2+ stores for the use by the
developing fetus
Human Chorionic Somatomammotropin
- Humanchorionic somatomammotropin (hCS) is also called
human placental lactogen (hPL). - Initially believed to be necessary for breast development during
pregnancy and for milk production (lactation). - Women who do not make hCS during pregnancy because of a
genetic defect still have adequate breast development and milk
production. - Alteration of the mother’s glucose and fatty acid metabolism to
support fetal growth (glucose resistance)
> in the late stages of pregnancy, the foetus often uses as much
glucose as the entire body of the mother uses - During pregnancy, about 4% of women develop gestational
diabetes mellitus (GDM), with elevated blood glucose levels
caused by insulin resistance, similar to type 2 diabetes.
Parturition
- During the first 2 trimesters the uterus is quiet
- In third trimester uterus become more exitable and leads to
Braxton-Hicks false contractions - As parturition approaches cervix softens due to dissociation of
collagen fibers
> Relaxin produced by CL of pregnancy and placenta
> Relaxin also softens connective tissue between pelvic bones
Lactation – The mammary gland
lobes (15- 20) divided by adipose tissue – has nothing to do with ability to nurse
lobules contain glandular alveoli secrete milk in lactating female
milk is secreted into a series of secondary tubules
tubules converge to form a series of mammary ducts
converge to form a lactiferous duct – drains into tip of nipple
lumen expands to form an ampulla (milk accumulation)
high estrogen and progesterone prevent lactation before parturition
loss of placenta abruptly declines estrogen and prolactin levels and initiates lactation
Lactation – The suckling reflex
Breast milk benefits to infant
Breast milk benefits to mother
