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Parturition & Lactation (84)
What secondary messenger system is associated with oxytocin?
How do prostaglandins affect uterine smooth muscle?
contraction (via PLC) or relaxation (via cAMP)
What type of hormone is oxytocin?
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)?
increases number of myometrial gap junctions (makes coordinated and stronger contraction)
Review hormonal changes during pregnancy.
What happens to CRH and CRH-binding protein as birth approaches?
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.
What is the major cause of dystocia? Second most common cause?
cephalopelvic disproportion (baby being too large to come out quickly)
Name 7 hormones that work together to stimulate the growth and maturation of the mammary gland.
Name 2 hormones involved in deposition of fat tissue in the mammary gland.
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?
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?