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AN SC 312 > 5 - Female Endocrinology & Puberty > Flashcards

5 - Female Endocrinology & Puberty Flashcards

1
Q

What cells release FSH and LH? Inhibin?

A

FSH and LH released by Gonadotroph cells of anterior pituitary

Inhibin released by granulosa cells of the ovary

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2
Q

LH target

A

Theca interna & luteal cells of the ovary

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3
Q

Inhibin action

A

Inhibits FSH secretion

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4
Q

LH action

A

Ovulation, formation of corpus luteum, progesterone secretion

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5
Q

Hypothalamic center(s) in females

A

Surge center and tonic center

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6
Q

What does the surge center do? The tonic center?

A

Surge center releases large amounts of GnRH upon stimulation

Tonic center is a constant “drip” released in small concentrations

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7
Q

How is the hypothalamus inherently female?

A

Male hypothalamus is defeminized during embryogenesis and the GnRH surge center is eliminated

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8
Q

What interaction plays are important role in not defeminizing the female hypothalamus?

A

Estradiol with the carrier protein “alpha-fetoprotein”

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9
Q

Explain slides 10 and 11

A

In male hypothalamic development, testosterone is secreted by the testis which does not bind alpha-fetoprotein and diffuses into the brain through the blood-brain barrier. It becomes estradiol in the brain which defeminizes the hypothalamus.
In the female, estradiol is released by the ovaries and is bound by aFP in the bloodstream which prevents it from crossing the blood brain barrier, and the surge center develops.

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10
Q

Explain the positive and negative feedback loops of GnRH secretion by the hypothalamus?

A

Estradiol has positive feedback on GnRH production of the surge center
Progesterone has negative/modulatory feedback on GnRH production

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11
Q

What regulates FSH secretion of the ________ ________

A

Inhibin regulates secretion from anterior pituitary

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12
Q

Slide 13**

A

Super important

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13
Q

Puberty is…

A

the process of acquiring reproductive competence

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14
Q

Pubescent process in the female involves…

A

first ovulation, first estrus, ability to maintain pregnancy

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15
Q

What is the limiting factor to the onset of puberty? How?

A

Hypothalamus
Onset requires secretion of GnRH at frequency and quantity appropriate to stimulate gonadotropin (FSH and LH) release by anterior pituitary
Surge center of prepubertal female cannot release ovulatory levels of GnRH

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16
Q

Theories on why prepubescent surge center can’t release ovulatory levels of GnRH

A
  • Estradiol levels not high enough to provide adequate stimulation to the surge center
  • Hypothalamus not able to respond to Estradiol to produce adequate levels of GnRH (too sensitive to recognize + feedback; estradiol suppresses GnRH release)***
17
Q

Slides 19,20

A

Diagrams

18
Q

Age range of puberty in cattle, sheep, dogs, cats

A

Cattle = 8 (holstein) to 24 months

Sheep = 4-14 months

Dogs = 6-24 months

Cats = 4-12 months

19
Q

Factors affecting onset of puberty

A
  • Genetic background
  • Plane of nutrition
  • Rate of growth
  • Exposure to environmental cues
20
Q

Metabolic triggers of puberty

A

Blood glucose, blood fatty acids, blood leptin

21
Q

Growth and maturation result in more…

A

available energy for non-vital physiological functions such as reproduction

22
Q

What is leptin? What does it do?

A

Protein hormone expressed by adipocytes (fat cells)
Provides body with an index of nutritional status (increase fat = increase leptin)
Works by affecting hypothalamic centers (feeding beh, hunger, energy expenditure, repro fxn)

23
Q

What gene codes for the leptin protein

A

Ob gene
Knock it out = feeding disorder

24
Q

Slides 25-27

A

Diagrams

25
Q

What happened to ovariectomized lambs who could not oxidize glucose (use it for energy)

A

Decrease in LH secretion bc not enough glucose for GnRH surge
After GnRH injection, there was an LH surge

26
Q

How does puberty differ in dairy heifers fed high, moderate and low plane nutrition

A

Puberty occurs earlier and at a lower body weight with high plane nutrition

27
Q

What environmental conditions affect puberty

A
  • Photoperiod (seasonal breeders)
  • Social contact (male-female, female-female)
28
Q

How does boar exposure and gilt grouping affect puberty?

A

Exposure to boar accelerates puberty (with or without physical contact)
Gilts in small groups (2-3) had delayed puberty, large groups (>10) had normal puberty

AN SC 312 (31 decks)

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