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PHYSIOLOGY III > L5: The Luteal Phase > Flashcards

L5: The Luteal Phase Flashcards

1
Q

what phase of estrus is marked by
* low estrogen
* LH surge has just occured
* ovulation occurred recently

A

metestrus

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2
Q

what phase of estrus
* progesterone peaks and is sustained at high levels (ovulation suppressed)
* estradiol is low

A

diestrus

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3
Q

what phase of estrus
* maximum corpus luteum size
* elevated progesterone inhibits final follicular development

A

diestrus

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4
Q

what phase of estrus
* CL regresses (due to release of PGF2alpha) at the end of this phase is there if no pregnancy

A

Diestrus

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5
Q

granulosa cells secrete _______ and _______ to increase blood supply to the new corpus luteum

A

vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF)

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6
Q

what is luteal hormone output dependent on

A

basal LH levels- maintained by pulses of GnRH

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7
Q

how does LH stimulate steroidogenesis

A

by activating cholesterol desmolase

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8
Q

what enzyme is needed for progesterone synthesis in the granulosa cell

A

3B-Hydroxysteroid dehydrogenase (3B-HSD)

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9
Q

Progesterone is released when there is an active…?

A

corpus luteum

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10
Q

what are the effects of progesterone on the hypothalamus

A

negative feeback - blocks progesterone and estrogen priming

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11
Q

what are the effects of progesterone on the endometrium of the uterus

A

promotes conditions needed for a fertilized egg

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12
Q

what produces relaxin in the cow

A

Corpus luteum
(produced by placenta in other animals)

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13
Q

what is the target and function of relaxin

A

target: uterus, soft CT
function: synergistic effect w/ progesterone to maintain pregnancy

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14
Q

T/F: the CL has a limited lifespan

A

T
pig,horse,primate,cow: 10-14 d
ewe: 17 d
dog: up to 90 days

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15
Q

at the end of the luteal phase, CL becomes what

A

corpus albicans

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16
Q

corpus luteum regresses at the end of _______ if there is no pregnancy due to _____ released by uterus

A

diestrus
PGF2alpha

17
Q

the CL produces oxytocin in what animals

A

Cow

18
Q

the CL produces estradiol in what animals

A

primates, pigs, rats

19
Q

during the luteal phase, ______ maintains the corpus luteum

A

LH (release caused by GnRH pulses)

20
Q

at the end of the ____ phase, _____ terminates the CL and progesterone secretion

A

luteal
PGF2alpha

21
Q

what animals produce PGF2alpha in the endometrium of their uterus

A

cow, horse, pig, sheep

22
Q

what is luteolysis

A

CL regression

23
Q

what stimulates luteolysis

A

estrogen/progesterone and oxytocin

24
Q

what are the 2 main effects of PGF2alpha

A
  1. opens Ca channels in granulosa cells, induces apoptosis through high intraceullar Ca
  2. Activation of PKC which inhibits mitochondrial transport of cholesterol and progesterone synthesis
25
Q

where does the initial signal for oxytocin positive feedback come form

A

posterior pituitary

26
Q

what signals the release of luteal oxytocin that signals back to the uterus

A

PGF2alpha

27
Q

what is the role of oxytocin acting through positive feedback on the corpus luteum

A

oxytocin leads to destruction of CL
oxytocin signals uterus to produce PGF2alpha which destroys CL

28
Q

in horses, PGF2alpha is released into the ______ blood from either of the uterine horms

A

systemic blood

29
Q

what is the vascular pathway for PGF2alpha in cows and sheep?

A

PGF2alpha is produced in uterus endometrium, **released into ovarian veins **and is transferred to the ipsilateral ovarian artery through a counter current exchange mechanism

30
Q

what is the effect of endometritis on the luteal phase in cows

A

it increases the time of the luteal phase

31
Q

Prolactin (PRL) is secreted from the ______ or the ______ dyring late stage pregnancy in the bitch and rat

A

anterior pituitary
endometrium

32
Q

what is the target of prolactin (PRL) in the rat, bitch and ewe? What is the target in mammals

A

rat , bitch, ewe: targets the CL
all mammals: targets mammary glands

33
Q

what is the effect of prolactin

A

luteotropic functions, required for initiation and maintenance of milk synthesis

34
Q

what suppresses prolactin

A

dopamine

35
Q

use of anti prolactin drugs (dopamine agonists or serotonin antagonists) in the bitch will induce _____ in days 4-48 of cycle or induce _______ and cause _______ if given mid pregnancy

A

estrus if given during days 4-48
if given mid-pregnancy, will induce luteolysis and cause abortion

36
Q

what (and when) stimulates the release of prolactin in the bitch

A

increasing levels of estrogen during late diestrus

37
Q

what stimulates prolactin release in rodents

A

copulation

PHYSIOLOGY III (31 decks)

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