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Reproduction > Chapter 6 > Flashcards

Chapter 6 Flashcards

1
Q

Where does puberty start?

A

at the level of hypothalamus

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2
Q

What center do males have operational?

A

only the tonic center

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3
Q

What centers do females have operational?

A

tonic and surge

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4
Q

Can estrogen cross the blood-brain barrier?

A

no

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5
Q

Can testosterone cross the blood-brain barrier?

A

yes

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6
Q

What hormone directly takes the surge center out of the male?

A

estrogen

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7
Q

Where does hormonal regulation begin?

A

fetus

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8
Q

Where is puberty initiated?

A

hypothalamus

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9
Q

Male -> spermatogenesis

A

yes

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10
Q

Female -> follicular spermatogenesis

A

yes

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11
Q

How should we think of reproduction?

A

a series of events (dimmer sweitch)

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12
Q

What is required for puberty to be initiated?

A

specific GnRH frequency and quantity of secretion

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13
Q

What is GnRH amplitude and frequency influenced by?

A

nutrition, environmental or social cues, genetics

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14
Q

What does the tonic center like to respond to?

A

negative feedback (testosterone in the male)

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15
Q

What drives the levels of testosterone in a male?

A

LH

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16
Q

What drives the levels of LH in a female?

A

estrogen

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17
Q

Progesterone is high when estrogen is low cause it is being produced in the corpus luteum.

A

yes

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18
Q

When is puberty achieved in the female?

A

when the surge center is activiated

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19
Q

When is puberty achieved in the male?

A

when the tonic center is activated

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20
Q

How do we use RIAs?

A

We use them to test for progesterone to test for ovulation, the corpus luteum produces the progesterone that is created with ovulation.

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21
Q

What are some variations in puberty onset/affect the secretion of GnRH? Hold true, external factors, genetic?

A

degree of fatness, environmental/social cues (other sex around), season born, photoperiod, density of groups of the same sex, genetics (breed) variations

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22
Q

The hypothalamus is inherently ____. _____ defeminizes the hypothalamus during embryogenesis and _____ the GnRH surge center in the male.

A

female; testosterone; eliminates

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23
Q

What binds to estradiol (estrogen) and prevents it from crossing the blood-brain barrier?

A

alpha-fetoprotein

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24
Q

Does LH surge in males?

A

no, it remains a pulsatile pattern

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25
Q

How often do estradiol and LH surge in females?

A

every 20 seconds

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26
Q

What must the female reach before puberty can be achieved?

A

threshold body size

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27
Q

Hypothalamic secretion of GnRH before and after puberty?

A

Figure 6-3, pg 131

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28
Q

LH frequency before and after puberty?

A

Figure 6-4, pg 132

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29
Q

What does the surge center like to respond to?

A

positive feedback

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30
Q

The hypothalamus is inherently what?

A

Female

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31
Q

What does testosterone do to the hypothalamus during embryogenesis? What does testosterone turn into?

A

defeminizes and estradiol

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32
Q

What does testosterone eliminate in the male?

A

surge center

33
Q

What makes the female hypothalamus not get defeminized like the male hypothalamus?

A

alpha-fetoprotein

34
Q

Alpha-fetoprotein is a?

A

glycoprotein synthesized in the embryonic yolk sac

35
Q

Continued postnatal exposure to what is required for complete rendering of the surge center in the male?

A

androgens

36
Q

Where is the surge and tonic center located?

A

hypothalamus

37
Q

Puberty can be defined as?

A

the ability to accomplish reproduction successfully

38
Q

What is the fundamental requirement for puberty?

A

the secretion of GnRH at appropriate frequencies and quantities to stimulate gonadotropin release by the pituitary

39
Q

What are the most important drives of pubertal onset and considered the limiting factor for the pubertal onset?

A

the presynaptic neurons that provide information to GnRH neurons

40
Q

What can these presynaptic neurons be influenced by?

A

plane of nutrition, certain environment exposure/social cues, genetics

41
Q

What two general factors impact the development of the hypothalamic GnRH neurons in the female?

A

development of a threshold body size and exposure to certain environmental/social cues

42
Q

What are the different onsets of puberty in females definitions?

A

age at first estrus, ovulation, female can support pregnancy without deleterious effects

43
Q

What are the different onsets of puberty in males definition?

A

age when behavioral traits are expressed, first ejaculation, when spermatozoa first appear in ejaculate, and when the ejaculate contains a threshold number of spermatozoa

44
Q

Mean Age (range) of Puberty for Bovine in males?

A

11 months

45
Q

Mean Age (range) of Puberty for Bovine females?

A

11 months

46
Q

Mean Age (range) of Puberty for Canine males?

A

9 months

47
Q

Mean Age (range) of Puberty for Canine in females?

A

12 months

48
Q

Mean Age (range) of Puberty for Equine in males?

A

14 months

49
Q

Mean Age (range) of Puberty for Equine in females?

A

18 months

50
Q

Mean Age (range) of Puberty for Feline in males?

A

9 months

51
Q

Mean Age (range) of Puberty for Feline in females?

A

8 months

52
Q

Mean Age (range) of Puberty for Ovine in males?

A

7 months

53
Q

Mean Age (range) of Puberty for Ovine in females?

A

7 months

54
Q

Mean Age (range) of Puberty for Porcine in males?

A

7 months

55
Q

Mean Age (range) of Puberty for Porcine in females?

A

6 months

56
Q

What is the major factor limiting the onset of puberty?

A

The failure of the hypothalamus to secrete sufficient quantities of GnRH to cause gonadotropin release

57
Q

What is the preovulatory GnRH surge?

A

GnRH neurons firing frequently and releasing large quantities of GnRH

58
Q

What needs to happen before ovulation can occur?

A

full neural activity of the surge center

59
Q

What does the preovulatory GnRH surge cause?

A

preovulatory LH surge

60
Q

What does estradiol do in the surge center?

A

Trigger firing of GnRH neurons

61
Q

What happens prior to puberty when discussing the low-frequency GnRH pulses?

A

there is an insufficient stimuli to cause the anterior lobe of the pituitary to release FSH and LH at high levels

62
Q

As puberty approaches in the male, what do the GnRH neurons (hypothalamic sensitivity) become less sensitive to?

A

the negative feedback of testosterone and estradiol

63
Q

What is the surge center considered in prepubertal female?

A

dormant

64
Q

What type of feedback does the male system have?

A

negative feedback

65
Q

What types of feedback does the female system have?

A

positive and negative feedback

66
Q

Hypothalamic neurons that regulate GnRH secretion detect what changes in blood glucose and fatty acids?

A

moment-to-moment

67
Q

The amount of ___ is directly related to the amount of fat in the body?

A

leptin

68
Q

What may acts directly on GnRH neurons as a direct synaptic connection?

A

kisspeptins

69
Q

The timeline of puberty assumes what two things are adequate?

A

nutrition and growth

70
Q

Pubertal onset cannot be accelerated in animals that have not achieved the appropriate?

A

metabolic body size to trigger hypothalamic responsiveness to estradiol

71
Q

What causes the mediation of social cues when it comes to the onset of puberty in many mammalian species?

A

pheromonal substances

72
Q

Exposure to what accelerates puberty in males?

A

to a boar

73
Q

Large groups =

A

normal puberty

74
Q

Small groups =

A

delayed puberty

75
Q

Is there a correlation between growth rate and exposure to the bull when it comes to how long it takes to reach puberty?

A

yes

76
Q

Is there a correlation between growth rate and exposure to the bull when it comes to how long it takes to reach puberty?

A

yes

77
Q

The surge center primarily responds to what feedback?

A

positive

78
Q

Positive feedback?

A

When estradiol concentrations reach a certain threshold and this causes a massive discharge of GnRH from the surge center.

Reproduction (11 decks)

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