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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
How often do estradiol and LH surge in females?
every 20 seconds
26
What must the female reach before puberty can be achieved?
threshold body size
27
Hypothalamic secretion of GnRH before and after puberty?
Figure 6-3, pg 131
28
LH frequency before and after puberty?
Figure 6-4, pg 132
29
What does the surge center like to respond to?
positive feedback
30
The hypothalamus is inherently what?
Female
31
What does testosterone do to the hypothalamus during embryogenesis? What does testosterone turn into?
defeminizes and estradiol
32
What does testosterone eliminate in the male?
surge center
33
What makes the female hypothalamus not get defeminized like the male hypothalamus?
alpha-fetoprotein
34
Alpha-fetoprotein is a?
glycoprotein synthesized in the embryonic yolk sac
35
Continued postnatal exposure to what is required for complete rendering of the surge center in the male?
androgens
36
Where is the surge and tonic center located?
hypothalamus
37
Puberty can be defined as?
the ability to accomplish reproduction successfully
38
What is the fundamental requirement for puberty?
the secretion of GnRH at appropriate frequencies and quantities to stimulate gonadotropin release by the pituitary
39
What are the most important drives of pubertal onset and considered the limiting factor for the pubertal onset?
the presynaptic neurons that provide information to GnRH neurons
40
What can these presynaptic neurons be influenced by?
plane of nutrition, certain environment exposure/social cues, genetics
41
What two general factors impact the development of the hypothalamic GnRH neurons in the female?
development of a threshold body size and exposure to certain environmental/social cues
42
What are the different onsets of puberty in females definitions?
age at first estrus, ovulation, female can support pregnancy without deleterious effects
43
What are the different onsets of puberty in males definition?
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
Mean Age (range) of Puberty for Bovine in males?
11 months
45
Mean Age (range) of Puberty for Bovine females?
11 months
46
Mean Age (range) of Puberty for Canine males?
9 months
47
Mean Age (range) of Puberty for Canine in females?
12 months
48
Mean Age (range) of Puberty for Equine in males?
14 months
49
Mean Age (range) of Puberty for Equine in females?
18 months
50
Mean Age (range) of Puberty for Feline in males?
9 months
51
Mean Age (range) of Puberty for Feline in females?
8 months
52
Mean Age (range) of Puberty for Ovine in males?
7 months
53
Mean Age (range) of Puberty for Ovine in females?
7 months
54
Mean Age (range) of Puberty for Porcine in males?
7 months
55
Mean Age (range) of Puberty for Porcine in females?
6 months
56
What is the major factor limiting the onset of puberty?
The failure of the hypothalamus to secrete sufficient quantities of GnRH to cause gonadotropin release
57
What is the preovulatory GnRH surge?
GnRH neurons firing frequently and releasing large quantities of GnRH
58
What needs to happen before ovulation can occur?
full neural activity of the surge center
59
What does the preovulatory GnRH surge cause?
preovulatory LH surge
60
What does estradiol do in the surge center?
Trigger firing of GnRH neurons
61
What happens prior to puberty when discussing the low-frequency GnRH pulses?
there is an insufficient stimuli to cause the anterior lobe of the pituitary to release FSH and LH at high levels
62
As puberty approaches in the male, what do the GnRH neurons (hypothalamic sensitivity) become less sensitive to?
the negative feedback of testosterone and estradiol
63
What is the surge center considered in prepubertal female?
dormant
64
What type of feedback does the male system have?
negative feedback
65
What types of feedback does the female system have?
positive and negative feedback
66
Hypothalamic neurons that regulate GnRH secretion detect what changes in blood glucose and fatty acids?
moment-to-moment
67
The amount of ___ is directly related to the amount of fat in the body?
leptin
68
What may acts directly on GnRH neurons as a direct synaptic connection?
kisspeptins
69
The timeline of puberty assumes what two things are adequate?
nutrition and growth
70
Pubertal onset cannot be accelerated in animals that have not achieved the appropriate?
metabolic body size to trigger hypothalamic responsiveness to estradiol
71
What causes the mediation of social cues when it comes to the onset of puberty in many mammalian species?
pheromonal substances
72
Exposure to what accelerates puberty in males?
to a boar
73
Large groups =
normal puberty
74
Small groups =
delayed puberty
75
Is there a correlation between growth rate and exposure to the bull when it comes to how long it takes to reach puberty?
yes
76
Is there a correlation between growth rate and exposure to the bull when it comes to how long it takes to reach puberty?
yes
77
The surge center primarily responds to what feedback?
positive
78
Positive feedback?
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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