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Mammalian Reproduction > Chapter 6 > Flashcards

Chapter 6 Flashcards

Puberty

1
Q

What is puberty?

A

Development of reproductive competence

it is a process not an event

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2
Q

What other factors influence puberty?

A

nutrition, age, genetics (EPDs),

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3
Q

True of False. hypothalamus is different in male vs. females

A

True

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4
Q

The hypothalamus secretes GnRH which controls release of FSH and LH, therefore gonadal function, Where are their + or - feedbacks?

A

positive feedback in surge center

negative feedback in tonic center

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5
Q

Ability of hypothalamus to produce sufficient GnRH is the limiting factor in inducing __________?

A

puberty

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6
Q

What must GnRH neurons must be able to do what two things?

A

able to fire frequently

release large quantities of GnRH

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7
Q

Gonads in pre- pubertal animals will react to exogenous _____ and _________

A

FSH and LH

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8
Q

Define Puberty Female (4 ways)

A
  1. age at first estrus/menses- visual
  2. Age at 1st ovulation, how do you observe this?
    a. CL key to ovulation observation/ confirmation
  3. Age at when pregnancy can be fully supported
    a. cycles/ ovulation start prior to this
  4. Blood, LH, reflection of GnRH secretion
    a. Done by an assay (hormone in blood)
    b. GnRH smaller quantities in blood vs. LH
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9
Q

Define Puberty Male (4 ways)

A
  1. age that spermatozoa appear in ejaculate or urine
  2. 1st ejaculation
  3. Age of repro behavior expressed
    a. sooner that viable spermatozoa
  4. MOST IMPORTANT! Sufficient sperm concentration to maintain a pregnancy
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10
Q

True of False. certain internal or social factors influence the onset of puberty in the female.

A

False, external

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11
Q

True or False. the female must reach a threshold body size before puberty can be achieved.

A

True

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12
Q

What do the testis secreted?

A

T4

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13
Q

T4 enters blood, carried to all tissues including _____?

A

brain

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14
Q

Can T4 cross blood brian barrier?

A

yes

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15
Q

What converts T4 to estradiol?

A

aromatase

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16
Q

When aromatase defeminize surge center what happens?

A

surge center does not develop

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17
Q

does the male have both surge and tonic center?

A

No, just a tonic center

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18
Q

What does ovaries secrete?

A

estradiol

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19
Q

What happens when estradiol enters the blood?

A

immediately bound by alpha fetoprotein

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20
Q

What type of protein is a alpha fetoprotein?

A

Glycoprotein: produced by fetal liver, most abundant plasma protein
is an osmotic regulator

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21
Q

Can alpha fetoprotein cross the blood brain barrier?

A

NO, allowing development of surge center

22
Q

Do females have both surge and tonic centers? If so what are their functions?

A

yes
Tonic: pulse frequency of GnRH
surge: high amplitude pulses of GnRH

23
Q

What dictates puberty and reproduction?

A

pulsatile releases of hormones

24
Q

Puberty of Female vs. Male

A

Female surges: estradiol causing GnRH and LH surge (pre ovulatory). Do not always have an egg ready
Male: low amplitude episodes of GnRH pulses every several hours. Prompt LH that stumulus testis to secrete T4. Can always secret semen

25
Q

Basal pulses

A

low amplitude and low frequency pulses of GnRH

26
Q

what is E2 bound by before birth?

A

alpha fetoprotein

27
Q

After puberty in the female what happens?

A

high amplitude and frequency of GnRH cause pre-ov surge

28
Q

Before puberty (both species) what happens?

A

low amplitude and low frequency pulses of GnRH

29
Q

How does the surge center develop full neural activity?

A

Kisspeptins control the release of GnRH allows females to hit puberty and allows males to make spermatozoa.

30
Q

In males, PosLow amplitude high frequency every several hours, promote LH and FSH to allow ________?

A

spermatogenesis

31
Q

key to starting puberty…

A

Kisspeptins -> GnRH (kisspeptins control GnRH secretion)

32
Q

Where do Kisspeptins live?

A

Hypothalamus… synapse directly on GnRH neurons

Known as the gateway keepers

33
Q

4-5 months before puberty what is the pulse and LH levels?

A

both low

34
Q

T or F. is the surge center functional in prepurbertal in females

A

true

35
Q

What is the limiting factor to why animals do not have GnRH surge? (prepubertal female)

A

E2 is too low

36
Q

What regulates GnRH secretion?

A

Kisspeptin neurons “Gatekeepers”

37
Q

Why is E2 too low in prepurbertal female?

A

Follicles are not stimulated to secrete it

38
Q

What inhibits kisspeptin neurons?

A

E2

39
Q

What do kisspeptins react to?

A

negative feedback of E2

40
Q

What happens when there is a negative feedback of E2?

A

Kisspeptins become inactive and lower the release of GnRH

41
Q

What happens to kisspeptins after so much E2?

A

Kisspeptins loose sensitivity causing an increase in GnRH secretion and then increase in FSH and LH along with E2…. causing more kisspeptins to loose more sensitivity… allowing the female to reach puberty

42
Q

in the male, GnRH looses sensitivity to?

A

testoserone

43
Q

What factors influence pubertal onset in the male?

A

Metabolic (glucose, FA)
Social (group size, male)
Environment (photoperiod, season of birth)

44
Q

Why follicles not be secreted? (prepubertal female)

A

FSH and LH is too low

45
Q

Why is FSH and LH to low? (prepubertal Female)

A

GnRH is too low

46
Q

What impacts the onset of puberty?

A

nutritional status

47
Q

Does the male contain a surge center?

A

No

48
Q

What must happen to start purberty?

A

Change hypothalamic sensitivity to E2 to T

49
Q

What does an increase in GnRH that causes and increase in FSH and LH cause on development side of things?

A

ovarian and testicular development

50
Q

The Threshold of E2 causes what?

A

GnRH surge, ovulation, and puberty

51
Q

word for complications during birth

A

dystocia

Mammalian Reproduction (10 decks)

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