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Physiology III > Lecture 6: Female Reproductive Physiology: Factors modulating female cyclicity > Flashcards

Lecture 6: Female Reproductive Physiology: Factors modulating female cyclicity Flashcards

1
Q

What is puerperium

A

Uterine recovery time

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2
Q

Mares have a ___puerperium and therefore ___probability of conception at the first postpartum estrus

A

Short, good

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3
Q

what is gestation period for horses

A

330-345

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4
Q

When does the estrus cycle start after foaling

A

5-8 days after foaling

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5
Q

When does ovulation occur after foaling

A

10 days

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6
Q

To breed horses yearly, breeders must take advantage of ____

A

Foal heat

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7
Q

What happens if you breed mare on 2nd heat

A

Mare will eventually miss a year of breeding when the season comes too late

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8
Q

Foal heat: ___ + ___

A

345 +7= 352 < a year

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9
Q

2nd heat= ___ + ___

A

345 +28= 373 > a year

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10
Q

What regulates female reproduction cyclicity

A

Hypothalamus

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11
Q

What are the external modulators factors that influence the timing of cyclicity in the female

A

Photoperiod/season
Lactation
Social factors/phermones
Nutrition
Age

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12
Q

What is polyestrous and what species fall under this category

A

Year round breeders
Cow, sow, humans

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13
Q

What is seasonally polyestrous and what species fall under this category

A

Several estrous cycles followed by an anestrous
Horse, cat, sheep, goat

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14
Q

What is monoestrous and what species fall under this category

A

One estrous cycle followed by a prolonged anestrous

Dog, wolf, bear

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15
Q

Anestrous is characterized by low ___ release and low ____ activity

A

Low estrogen and reproductive activity

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16
Q

What are long day breeders and what species fall under this category

A

Breed when days get longer

Mares and queens

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17
Q

When do mares typically breed

A

March-October

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18
Q

When do queens typically breed

A

January-October

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19
Q

What are short day breeders and what species fall under this category

A

Breed when days get shorter
Sheep, goats, dear, and elk

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20
Q

When do sheep and goats typically breed

A

July-February

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21
Q

__is the primary controller of reproductive cycles

A

Light

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22
Q

___sensitives the HPG axis by releasing GnRH

A

Light

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23
Q

What are some other factors besides light that trigger the HPG axis

A

Sexual stimuli- phermones, sound, visual

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24
Q

In females ___is the main modulator of female ovarian cycle

A

Light

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25
What additional factors influence the female ovarian cycle
Lactation, nutrition, social condition, age
26
The pineal gland releases ___in response to darkness
Melatonin
27
Light stimulates the retina and activates _____ through ____ tract
Hypothalamic suprachiasmastic nucelus (SCN) through the retinal hypothalamic tract
28
What inhibits the pineal gland to decrease melatonin
SCN
29
SCN inhibits the pineal gland to decrease melatonin to alter the timing of what 2 things
1. Day-night activity 2. Seasonal breeding activity
30
Describe the role of light in reproductive timing of long day breeders
1. Melatonin excites RFamide-related peptide (RFRP-3) neurons 2. RFRP-3 neurons activate kisspeptin in hypothalamus 3. Kisspeptin stimulates GnRH neurons
31
Describe the role of light in reproductive timing of short day breeders
1. Melatonin excites RFamide-related peptide 3 (RFRP-3) neurons 2. RFRP-3 neurons inhibit kisspeptin 3. Therefore, inhibiting release of GnRH
32
Clinical Correlation: Mare on foal heat day 7, was not bred, 40 days have passed and no estrus, no response to teasing by stallion. Small, constricted cervix with considerable tone but quiescent, normal ovaries, one with large 35mm follicles What is likely cause? What test can be run? Treatment?
Persistent corpus luteum, follicles > 30mm Test: serum progesterone 1-2 ng/mL (peak cycle progesterone= 3 ng/mL) Treatment: administer PGF2alpha monitor for estrus in 5-7 days
33
Clinical correlation: foal heat 7 days after birth, was not bed, 40 days have passed and no estrus, no response to teasing by stallion. Small cervix that is not closed or tight. Uterus is small and flaccid, inactive ovaries with no follicles > 10mm What is the likely cause? Test? Treatments?
Mare is in anestrus, mares that foal early can be adversely affected by the short photoperiod and become anestrus Test: serum estrogen and progesterone= low Treatment #1: artificial manipulation of photoperiod Treatment #2: breed on the foal heat to avoid the odds that the mare foaling early in the year will re-enter anestrus during the foal heat ovulation
34
How does phototrophic stimulation in mares work
Artificial lighting provided for ~60 days can induce early breeding Stimulates return to estrus
35
How does seasonality affect age and puberty ex: lambs
Spring born lambs come into puberty at a younger age than their fall born flock mates Due to increase day length
36
Do gilts in small or large herds enter puberty later
Gilts in small herds enter later than in large groups
37
Gilts exposed to a boar even in small groups will reach puberty ____
Earlier
38
How does lactation affect ovulation in sows
Complete inhibition of ovulation
39
How does lactation affect ovulation in cats, beef cows, primates
Partial suppression of ovulation
40
Suckling inhibits ___ which releases ___
Dopamine, prolactin
41
When dopamine is suppressed, lactrotrophs release prolactin, prolactin inhibits ____ synthesis
GnRH
42
Describe the suckling/lactaiton signaling
1. Stimulus from suckling signals to hypothalamus 2. Inhibit dopamine release from arcurate nucleus 3. Decreased dopamine release removes inhibition that is usually put on lactrotrophs in anterior pituitary, leading to prolactin release 4. Prolactin stimulates milk production in the breast 5. Oxytocin is also released from PVN and SON. Travels to breast and myoepithelial cells 6. Neurons inhibit arcurate and preoptic area, these decreasing GNRH production. 7. Reduced stimulation of gonadotrophs inhibits ovarian cycle
43
Suckling in cows: when the number of suckling sessions is between 3-20/day the amplitude and pulse frequency of blood ___ are low and cow remains in ____
LH, anestrus
44
Suckling in cows: when the number of suckling sessions is limited to two or less per day the amplitude and pulse frequency of ___ increases and cow will begin to cycle
LH
45
How does body weight effect ovulation
Low body weight can delay ovulation to end of winter
46
____ body weight and percent fat are associated with greater reproductive activity
Higher
47
Animals with better body composition can achieve a ____ pregnancy rate
Higher
48
What do insulin and leptin do to appetite
Suppress
49
What does gherlin do to appetite
Stimulate
50
What hormone signals steroidogenesis
growth hormone-IGF-1
51
What hormone induces steroidogenesis
Thyroid hormone
52
Blood glucose levels are detected in the ___
Hypothalamus
53
Leptin is released by ___ in response to increase in ___ volume
Adipocytes and adipocyte
54
Release of leptin is proportional to the amount of ___
Energy stored
55
Leptin targets __ neurons in hypothalamus
Kisspeptin
56
Leptin targeting kisspeptin neurons in hypothalamus affects release of ____ from the ____
GnRH from the preoptic nucleus
57
Fasting in heifers is associated with ___leptin and ___LH pulse frequency
Low leptin and lower LH pulse frequency
58
Food deprived mice show ___estrus which is reversible by ___ treatment
Delayed estrus, leptin treatment
59
Leptin experimentally administered to young mice ____entry to puberty
Accelerates
60
___ stimulates pro-opiomelanocortin (POMC) neurons in the arcurate nucleus
Leptin
61
POMC neurons regulate…
Appetite, metabolism and body weight
62
What does 2-deoxyglucose (2-DG) experimentally induce
Starvation
63
What happens to LH levels in sheep after administered 2-DG
LH disappears
64
To maintain a yearly calving interval, cows must become pregnant by ___ days after calving
80-85 days
65
In first lactation trimester, energy requirement for milk productions ____ energy intake
Exceeds
66
Milk production in cows peaks at weeks ___
4-6
67
Feed intake in lactating cows peaks at weeks ___
9-11
68
What is flushing
Management term for providing high quality feeds, usually grains prior to the start of the breeding to increase reproductive performance
69
Increase in energy and/or protein will ___ incidence of ovulation
Increase
70
Increase in energy and/or protein intake can produce and release multiple ___ in small ruminants and sows
Eggs
71
How is fertility reduced in old age
Reduced follicle number, cessation of live births, irregular cycles, increased cycle length, increased inter birth interval
72
Ovarian exhaustion of the follicle is ___ of reproductive senescence
Pacemaker
73
How are estrogen, gonadotropin/LH and FSH levels affected in older females
Reduced estrogen LH levels insufficient to trigger ovulation Elevated FSH due to fever follicles
74
During old age is the estrus cycle shorter or longer
Shorter

Physiology III (34 decks)

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