Repro Flashcards
(233 cards)
Which individual triggers the onset of parturition, Fetus or Mother?
fetus
Maturation of the HPA axis of the fetus needs to occur first to trigger parturition. This entails the hypothalamus secreting ___________, which goes to the anterior pituitary and stimulates _________ to be released. This hormones stimulates the adrenal cortex to produce __________. All of which allows the fetus to become “stressed.”
corticotropin releasing hormone (CRH) adrenocorticotropic hormone (ACTH) this hormone cortisol
The fetus must reach “capacity” to trigger parturition. What does this mean?
As the fetus grows, space within the uterus becomes limited. This is a stimulus for ACTH secretion by the fetal pituitary, and subsequent cortisol secretion.
the cumulation of HPA axis maturation and _____________ = FETAL STRESS
fetus reaching mature size
the fetal pituitary stimulates secretion of adrenal ________.
cortisol
Fetal cortisol causes a decrease in ________ and an increase in estrogen.
Estrogen causes increased secretions by repro tract, increased myometrial contractions, increased pressure, increased cervical stimulation, increased oxytocin.
progesterone
T/F: enzymes that convert cholesterol to progesterone are upregulated before parturition and enzymes that convert progesterone to estrogen are down regulated
FALSE – down regulated chol –> prog, upregulate prog –> estrogen
overall outcome = decrease prog, increase E2
T/F: in most species, testing progesterone is not very useful because it does not “drop” until right before parturition will occur.
true
what is the purpose of progesterone decreasing during initiation of parturition?
removes the block on uterine contractions
remember, progesterone prevents contractions so that the fetus stays within the uterus during gestation.
What is the purpose of increased estrogen during initiation of parturition?
uterus will become responsive to induction of contractions
oxytocin receptors will be induced
pelvic ligaments will relax
vulva swells/softens
Cortisol increases production of ________, which is important for lung maturation. This is critical for when the fetus takes its first breath in preventing the lungs from collapsing.
surfactant
Expansion of the birth canal is mediated by what 2 hormones?
estrogen and relaxin
maternal behavior is mediated by what hormone?
oxytocin
synthesis and ejection of milk is mediated by what 2 hormones?
prolactin (synthesis)
oxytocin (ejection/let down)
initiation of uterine contractions is mediated by what 2 hormones?
PGF and oxytocin
termination of pregnancy is ultimately determined by what hormone?
PGF
Mammary enlargement, colostrum production, enlargement + elongation of vulva, pelvic ligament relaxation and softening of perineum, as well as isolation and decreased appetite are all signs of …
impending parturition
these would be signs during stage I of parturition when estrogen is taking effect
Gestation of camelids and mares…
11-12 months
gestation for cattle
9 months
gestation for sheep and goats
5 months (150-152 days)
gestation for pigs
3 months, 3 weeks, and 3 days (114 days total)
What stage of parturition is described as:
1. relaxation/dilation of cervix
2. uterine contractions commence (oxytocin, PGF, E2)
3. fetus adopts birthing position
4. chorioallantois enters the vagina
first stage
What signs can be observed from the dam during the first stage of parturition?
- isolation
- decreased/non-existent appetite
- signs of colic (treading, looking at flank, restless, pawing ground)
- tail flagging/raising
- vaginal discharge
- milk/colostrum production
What is the term for when oxytocin is released from the pituitary and causes uterine contractions that lead to the fetus positioning itself within the birth canal and in doing so, the pressure triggers nerves that carry signals to the brain (PVN) to continue producing oxytocin. (positive feedback)
Ferguson reflex