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ASCI 341 > CH 6 Puberty > Flashcards

CH 6 Puberty Flashcards

1
Q

What does testosterone do to the brain?

A

“defeminizes” the brain and eliminates the GnRH surge center in male

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2
Q

What centers do males have? What centers do females have?

A

Female - surge and tonic center
Male - tonic center only

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3
Q

What is a-fetoprotein produced by? What does it bind to?

A

Produced by fetal liver

Binds to estradiol-17B and not testosterone

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4
Q

What does a-fetoprotein do in females?

A

alpha-fetoprotein binds to estradiol-17B, so it can’t cross the blood-brain barrier

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5
Q

What does a-fetoprotein do in males?

A

alpha-fetoprotein doesn’t bind to testosterone so it can cross the blood-brain barrier

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6
Q

What is aromatization and where does it occur?

A

Conversion of testosterone to estrogen-18B by aromatase

Occurs in the brain

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7
Q

What is puberty?

A

Ability to accomplish reproduction successfully

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8
Q

What does pubertal onset require?

A

Requires development of specific hypothalamic neurons so that there is release of adequate quantities of GnRH at appropriate frequencies

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9
Q

What are the 3 factors puberty is influenced by?

A
  • Acquisition of threshold body size
  • Exposure to certain environmental and social cues
  • Genetics of animal
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10
Q

What are the 3 different definitions for puberty onset in females?

A
  • Age at first estrus
  • Age at first ovulation
  • Age at which a female can support pregnancy
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11
Q

What are the 5 different definitions for puberty onset in males?

A
  • Age when behavioral traits are expressed
  • Age at first ejaculation
  • Age when spermatozoa first appear in ejaculate
  • Age when spermatozoa first appear in urine
  • Age when ejaculate contains threshold # of spermatozoa
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12
Q

What happens to GnRH pulse frequency after puberty?

A

^ pulse frequency
^ pulse amplitude

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13
Q

What is age of puberty influenced by?

A
  • breed
  • threshold of body size - degree of “fatness”
  • external or social factors
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14
Q

What are the external / social factors that influence age of puberty?

A
  • season of birth (sheep)
  • photoperiod at time of pubertal onset (sheep)
  • presence of opposite sex during peripubertal period (swine and cattle)
  • density of housing groups (same sex) (swine)
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15
Q

What causes an increase of GnRH pulses?

A

acquisition of ability to release high-frequency GnRH pulses from hypothalamic nuclei

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16
Q

Describe preovulatory GnRH surge

A

GnRH neurons must “fire” frequently and release large quantities of GnRH to indice the LH surge

17
Q

What does the tonic center do during the preovulatory stage?

A

Tonic center must also mature in function - regulates tonic frequency of LH surge

18
Q

What is the main endocrine profile difference between postpubertal males and females?

A

LH surges in female but there are no LH surges in males

19
Q

How does degree of “fatness” affect onset of puberty in newborns and growing neonates?

A

Newborn –> nutrients utilized for maintenance

Growing neonate –> energy consumption increases, body mass increases

This allows use of nutrients for non-essential functions like reproduction
Both age and “fatness” are important to onset of puberty?

20
Q

How does metabolic status induce puberty?

A

GnRH neurons are very sensitive to changes in glucose and fatty acids in the blood (females)

21
Q

What is leptin?

A

Hormonal peptide produced by fat cells (adipocytes)

22
Q

Where are leptin receptors located?

A

liver, kidney, heart, skeletal muscles, pancreas, anterior pituitary, and hypothalamus

23
Q

What does kisspeptin cause?

A

Smaller repro tract, never develop puberty when kisspeptin is taken away

24
Q

How do environmental and social conditions affect the onset of puberty?

A

In general, sensory neurons of optic and olfactory systems perceive environmental information –> deliver neural inputs to the GnRH neurons of hypothalamus

25
Q

What is a pheromone?

A

Chemical in urine recognized by olfactory system

ASCI 341 (13 decks)

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