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23 terms

Parturition & Lactation (84)

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What secondary messenger system is associated with oxytocin?
IP3/DAG
How do prostaglandins affect uterine smooth muscle?
contraction (via PLC) or relaxation (via cAMP)
What type of hormone is oxytocin?
peptide hormone
Describe the levels of the following hormones during the initiation of the birthing process: progesterone, CRH, estrogen.
decrease in progesterone levels

increase in circulating CRH levels

increase in estrogen levels
How does progesterone affect uterine smooth muscle (3)?
inhibits oxytocin receptor synthesis

stimulates cAMP production

inhibits release of prostaglandins that will excite the uterine smooth muscle

*overall "calming" effect
How does estrogen affect uterine smooth muscle (2)?
ripens cervix

increases number of myometrial gap junctions (makes coordinated and stronger contraction)
Review hormonal changes during pregnancy.
1
What happens to CRH and CRH-binding protein as birth approaches?
CRH increases

CRH-binding protein decreases
What is the purpose of placental secretion of CRH as birth approaches?
increases DHEA-S production
Just prior to birth, what are the 2 distinct sections of the uterus?
upper muscular section

lower thinner section
How does oxytocin affect the placenta?
induces placenta to release prostaglandins, which cause myometrial contractions
What is dystocia?
abnormally slow labor
Name 4 causes of dystocia.
cephalopelvic disproportion

conduction anesthesia

excessive sedation

fetal malposition
What is the major cause of dystocia? Second most common cause?
cephalopelvic disproportion (baby being too large to come out quickly)

excessive sedation
Name 7 hormones that work together to stimulate the growth and maturation of the mammary gland.
estrogens

progesterone

prolactin

hCS

cortisol

insulin

GH
Name 2 hormones involved in deposition of fat tissue in the mammary gland.
estrogens

prolactin
Name 2 hormones that inhibit milk production during pregnancy, and explain how they accomplish this task.
estrogens (prevent terminal differentiation)

progesterone (inhibits lactogenesis)
What action is the main regulator of prolactin secretion during lactation?
suckling
How does suckling affect hypothalamic release of dopamine?
decreases dopamine release
How does suckling affect hypothalamic release of prolactin releasing factor?
stimulates release of PRF
List 3 ways in which prolactin affects lactation.
increase milk production

promotes gene expression of milk proteins

stimulates lactose synthesis
List 3 ways in which prolactin affects reproduction.
decreases GnRH secretion (high levels)

galactorrhea amenorrhea in females/impotence in males

inhibits follicular development during breast feeding
What hormone allows milk to be ejected from the breast?
oxytocin