Physio of the Estrous Cycle Flashcards

1
Q

Who is involved in the endocrine regulation of the estrous cycle?

A

Hypothalamus: GnRH
Hypophysis: FSH and LH
Ovaries: estradiol, progesterone, inhibin
Uterus: Prostaglandin PF2a

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2
Q

What role does inhibin play in the estrous cycle?

A

Prevents the development of multiple follicles during ovulation. Only one follicle should ovulate.

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3
Q

What is the follicle producing from the primary stage to the Graffian stage?

A

Estradiol

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4
Q

What is the follicle producing after the Graffian stage (CH and CL)?

A

Progesterone

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5
Q

Where in the ovaries are follicles found?

A

Cortex

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6
Q

If ovulation without fertilization occurs, the uterus produces _____ to lyse the corpus luteum and begin another cycle.

A

Prostaglandin PGF2a

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7
Q

What are the committed follicles?

A

Follicles from the resting pool that are activated to begin growing

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8
Q

When is development of the follicle gonadotropin (FSH and LH) independent?

A

Up to the formation of the antrum.

  • Independent: primordial, primary, secondary
  • Responsive: preantral, antral
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9
Q

Gonadotropin dependent stages of follicle development

A

Antral, Graffian, up until ovulation

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10
Q

At what stage is the follicle most susceptible to atresia?

A

Preantral to early antral transition, during formation of the theca cell layer

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11
Q

Features of the corpus hemorrhagicum

A

Immediately after ovulation
Antrum collapses
Low progesterone levels

*will see bloody discharge in cows

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12
Q

Features of the corpus luteum

A

Theca interna and granulosa cells proliferate and differentiate into small and large luteal cells.

Progesterone levels increase

Large luteal cells also secrete oxytocin and relaxin

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13
Q

Area of the brain responsible for regular pulses of GnRH

A

Tonic GnRH Center of the hypothalamus.

*affected by internal and external (melatonin) signals

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14
Q

Area of the brain responsible for releasing bursts of GnRH to initiate ovulation.

A

Surge Center of the hypothalamus

  • female brain only!
  • w/out sufficient GnRH burst, surge of LH is not released and ovulation doesn’t occur
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15
Q

Effects of estrogen during ovulation

A
Thickening vaginal mucosa
Mucus secretion
Epithelial mitosis (endometrium)
Increased secretory and ciliary beat activity
Endometrial edema
Myometrial activity
Estrous behavior
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16
Q

Ovulation is initiated by a surge of ___, and then Theca interna cells begin to produce _______ rather than androstenedione.

A

LH, progesterone

17
Q

During ovulation, the corpus luteum secretes ______, which _____endometrial secretion, _____ myometrial activity, and primes the brain to enhance the effects of ______.

A

During ovulation, the corpus luteum secretes PROGESTERONE, which INCREASES endometrial secretion, REDUCES myometrial activity, and primes the brain to enhance the effects of ESTROGEN.

18
Q

If fertilization does not occur, the uterine endometrium produces ______, which is released into the ____ ____, enters the ____ ____, and is delivered to the ovary where it causes lysis of the ____ _____.

A

If fertilization does not occur, the uterine endometrium produces PGF2a, which is released into the UTERINE VEIN, enters the UTERINE ARTERY, and is delivered to the ovary where it causes lysis of the CORPUS LUTEUM.

19
Q

Luteolysis is _______ in ruminants and _____ in the mare and sow

A

ipsilateral, systemic

20
Q

Progesterone from the CL forms a negative feedback loop with the hypothalamus to ensure what?

A

Continued tonic release of LH from the adenohypophysis to support the CL until PGF2a causes CL regression

21
Q

Inhibin forms a negative feedback loop with the pituitary to regulate what?

A

FSH release

22
Q

Melatonin _____ GnRH release in short day breeders like small ruminants, and _____ GnRH release in long day breeders like horses.

A

Melatonin INCREASES GnRH release in short day breeders like small ruminants, and DECREASES GnRH release in long day breeders like horses.

23
Q

Definition of puberty

A

Age at which the body can produce adequate amounts of GnRH and respond to it.

  • acquisition of capability of sexual repro
  • production of gametes
  • onset of cyclicity in females
24
Q

Sexual maturity differs from puberty and involves

A

Body growth and adequate size for pregnancy/delivery/lactation

25
Q

What’s up with the pulse generator in juveniles?

A

That boi is dormant

26
Q

What adipocyte hormone senses ideal body size and maturity, and helps mediate the onset of puberty?

A

Leptin

27
Q

For contraception, the most efficient place to regulate GnRH production is…

A

at the hypothalamus

28
Q

Human and primate contraception works by…

A

preventing development of pre-ovulatory follicles

29
Q

3 phases of the estrous cycle

A

Follicular/Proliferative
Luteal
Quiescent

30
Q

Polyestrous animal. Not season specific.

A

Cow

31
Q

Monoestrous animal. Not season specific.

A

Dog

32
Q

Animals that are seasonally polyestrous

A

Horse

Sheep

33
Q

This phase of the ovarian cycle is estrogen dominated, includes proestrus and estrus, and involves development of follicles

A

Follicular/Proliferative

34
Q

This phase of the ovarian cycle takes place from ovulation to CL regression and is progesterone dominated.

A

Luteal/Secretory