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VMP824 Physiology/Microanatomy 2 > Lecture 27 3/22/24 > Flashcards

Lecture 27 3/22/24 Flashcards

1
Q

What is the estrous cycle?

A

interval between two ovulations

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2
Q

What are the phases of the estrous cycle, based on dominant structure?

A

-follicular phase
-luteal phase

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3
Q

What are the primary behavioral events during estrus?

A

-sexual receptivity
-copulation

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4
Q

What are the characteristics of the follicular phase?

A

-period from regression of CL to ovulation
-relatively short
-primary structures are growing dominant follicles
-follicles produce estradiol

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5
Q

What are the characteristics of the luteal phase?

A

-period from ovulation until CL regression
-longer phase
-dominant structure is corpora lutea
-CL produces progesterone

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6
Q

What are the stages of the estrous cycle?

A

-proestrus
-estrus
-metestrus
-diestrus

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7
Q

Which stages occur during the follicular phase?

A

-proestrus
-estrus

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8
Q

Which stages occur during the luteal phase?

A

-metestrus
-diestrus

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9
Q

What are the characteristics of proestrus?

A

-begins when progesterone declines
-terminates at onset of estrus
-follicle development and rise in estradiol

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10
Q

What are the characteristics of estrus?

A

-most recognizable stage
-peak of estradiol
-sexual receptivity and mating
-ovulation occurs

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11
Q

What is standing estrus?

A

the female’s willingness to accept a male for mating

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12
Q

What are the characteristics of metestrus?

A

-between ovulation and formation of functional corpora lutea
-initial development of CL
-transition from estradiol to progesterone

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13
Q

What are the characteristics of diestrus?

A

-mature phase of CL
-progesterone dominance
-period of maximum luteal function
-longest stage of estrous cycle
-ends when CL is destroyed

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14
Q

How does the estrous cycle compare to the menstrual cycle?

A

Estrous:
-interval between ovulations
-short follicular phase
-ovulation to begin cycle
Menstrual:
-interval between menses
-long follicular phase
-ovulation mid-cycle

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15
Q

What occurs during the proliferative and secretory phases of the menstrual cycle?

A

changes in endometrial thickness

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16
Q

What are the major events that occur during the follicular phase?

A

-elevated gonadotropins
-follicular growth
-preparation for ovulation
-sexual receptivity
-ovulation

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17
Q

What are the characteristics of ovulation?

A

-after luteolysis and absence of progesterone
-dominant follicle secretes large amount of estrogens
-feedback to surge center leads to LH peak

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18
Q

What happens after the surge center causes LH to peak?

A

-increase in PGE2 and blood flow
-increase in PGF2a
-increase in intrafollicular pressure
-disruption of connective tissue of follicle/weakening of follicle wall
-change from estradiol to progesterone
-removal of meiotic inhibition
-1st meiotic division

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19
Q

What are the roles of granulosa and theca cells?

A

-luteinization
-switch from estrogen to progesterone

20
Q

What is the role of LH?

A

induction of ovulation

21
Q

What is the role of luteotropin?

A

essential for maintaining CL

22
Q

What are the characteristics of progesterone?

A

-prepares uterus for initiation/maintenance of pregnancy
-negative feedback with hypothalamus and pituitary
-stimulates endometrial secretion
-reduces myometrial motility
-poor progesterone synthesis/secretion can lead to repro. failure

23
Q

What are the characteristics of the corpus luteum lifespan?

A

-lifespan is preprogrammed
-luteolysis occurs if animal is not pregnant
-maternal recognition of pregnancy prolongs CL lifespan

24
Q

Which hormones control luteolysis?

A

-oxytocin
-progesterone
-PGF2a

25
Q

What is maternal recognition of pregnancy?

A

mechanism that prevents PGF2a secretion and produces a luteotropic hormone that stimulates/prolongs CL

26
Q

How does the uterus control the duration of the CL lifespan?

A

-PGF2a production
-expression of oxytocin receptors

27
Q

What are the clinical uses of PGF2a?

A

-break CL and return animal to heat
-estrous synchronization
-short cycle
-abortion

28
Q

How does progesterone prevent PGF2a secretion during the first half of the estrous cycle?

A

by blocking the formation of oxytocin receptors

29
Q

How do spontaneous ovulators differ from induced ovulators?

A

-spontaneous ovulators have endocrine triggers
-induced ovulators have gonadotropin release in response to copulation

30
Q

Which animals exhibit polyestrus?

A

-cow
-cat
-pig
-rodent

31
Q

Which animals exhibit seasonal polyestrus?

A

-horse
-cat

32
Q

Which animals exhibit monoestrus?

A

dog

33
Q

What is polyestrus?

A

uniform distribution of cycles regularly throughout the year

34
Q

How do long day breeders differ from short day breeders in seasonal polyestrus?

A

-long day breeders are in heat in spring and summer
-short day breeders are in heat in fall and winter

35
Q

What are the steps of the estrus cycle in the bitch?

A

-anestrus
-proestrus
-estrus
-diestrus

36
Q

Why is there a delay between ovulation and fertilization in the bitch?

A

primary oocytes are ovulated and fertilization cannot occur for 48-72 hours after ovulation

37
Q

Why is there no luteolysis or maternal recognition of pregnancy in dogs?

A

the estrus cycle is long enough that this step does not need to occur

38
Q

How long does it take for ovulation to occur in dogs after the LH peak?

A

3 days

39
Q

What is postestrus?

A

an interestrus period in cats that follows estrus in which there was no mating, no ovulation, no CL development, and thus no diestrus

40
Q

What are the characteristics of anestrus?

A

-lack of cyclicity
-lack of ovarian activity/no follicles or CLs
-insufficient GnRH from hypothalamus to stimulate gonadotropin secretion

41
Q

What causes anestrus?

A

-age
-pregnancy
-lactation
-nutrition
-season
-stress
-pathology

42
Q

How can anestrus be diagnosed?

A

-ultrasound of ovaries
-progesterone determination
-previous records of GnRH or progesterone supplementation

43
Q

How does true anestrus differ from pseudoanestrus?

A

-in true anestrus, the ovaries are small and inactive
-in pseudoanestrus, the ovaries are active, and there are other factors causing anestrus

44
Q

Which tests can be done to properly time insemination?

A

-vaginal cytology
-endocrine levels

45
Q

How are progesterone levels used to determine breeding day?

A

-measure progesterone levels every 1-2 days once vaginal discharge begins
-follow progesterone increase
-breed two days post ovulation (typically two insemination times)

46
Q

What is galactorrhea?

A

spontaneous development of mammary glands with secretions

47
Q

What are the characteristics of pseudopregnancy in dogs?

A

-occurs at end of diestrus
-associated with decline in progesterone
-decrease in progesterone triggers increase in prolactin
-prolactin causes clinical signs
-typically resolves with no intervention
-can occur following ovariohysterectomy

VMP824 Physiology/Microanatomy 2 (50 decks)

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