Comparative Reproduction Menstraul Cycle Flashcards

1
Q

What is menses/menstruation
When does it occur?

A

External loss of blood
Occurs after luteolysis at the beginning of the follicular phase

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2
Q

Which animal species show menstruation?

A

Apes
Old world monkeys

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3
Q

Average cycle length of a woman is how long

A

28 days

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4
Q

What are the 3 phases of the menstrual cycle?

A

1.14/15 day follicular phase; until Gonadotrophin surge is induced (called mid cycle surge)
2. 14 day luteal phase
3. Follicular phase again if pregnancy has not occured

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5
Q

What phase of menstrual cycle does menses occur

A

First few days of follicular phase

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6
Q

What are the 3 endometrial phases seen during menstrual cycle?

A

Menstrual phase
Proliferative phase
Secretory phase

(On anki)

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7
Q

During which endometrial phases are progesterone levels at their peak

During which endometrial phases are oestrogen levels at their peak

A

-Secretory phase

-Proliferative phase

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8
Q

Which endometrial phase do endometrium cells become fully grown and start secreting?

A

Secretory phase

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9
Q

What is function of progesterone during luteal phase of menstrual cycle

A

Stimulates repro tract & provides correct secretions for embryo

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10
Q

What occurs to the fully functional epithelial cells during menstrual cycle secretory phase if pregnancy does not occur

A

They start to shed; overtly expelled to the outside

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11
Q

What is menstrual flow

A

Endometrial tissues active and further grown in the secretory phase plus menstrual blood are expelled/ shed when progesterone is withdrawn at luteolysis (when pregnancy hasn’t occured- CL regression)

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12
Q

What are the hormone changes during menstrual cycle

A

Oestradiol starts rising in 2nd half of follicular phase and induces the mid-cycle LH surge

After ovulation progesterone rises due to CL development, and increased progesterone indicates the
luteal phase

The corpus luteum in the woman also secretes oestradiol (and inhibin A) which will suppress FSH
during the luteal phase

FSH rises after luteolysis (CL regression) at the onset of menses (=beginning of follicular phase, FP) which leads to a typical follicle wave emerging

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13
Q

DF dominant follicle selection occurs when?

A

At FSH decline, 1 week after luteolysis

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14
Q

How does dominant follicle stopnew follicular waves form occurring

A

Secretes Oestradiol and inhibin in the 2nd half of the FP suppressing FSH, so no new follicle wave

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15
Q

What are the similarities in the cow and mare menstrual cycle

A

Follicle dynamics, steroid function and CL lifespan very similar
Both show 2-wave & 3-wave cycles

Follicle dynamics:
Transient FSH rises—> follicle waves (major wave at beginning of follicular phase)—> selection of single dominant follicle

Role of steroids:
• oestradiol reduces FSH, induces GnRH surge
• progesterone reduces LH pulse frequency

CL lifespan 12-15 days

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16
Q

What are the differences in the cow and mare menstrual cycle

A

oestrous and menstrual cycles in the timing of follicle waves, the length of the follicular phase, and the CL function

CL function differences in:
• Secretion of inhibin A and oestradiol in addition to progesterone
• Luteolysis (passive = reduction in LH response leads to intra-luteal PGF2a and cytokine production causing apoptosis and autophagocytosis)

17
Q

What is menopause in woman

A

When ovulation ceases. Occurs once the number of primordial follicles has depleted. Cessation of ovulation for >1 year= menopause

18
Q

What age does menopause usually occur at?

A

51 years with range between 40-60years

19
Q

What occurs several years before menopause occurs

A

decline in oestradiol and increase in FSH

20
Q

What are side effects of menopause due to lack of Oestradiol/supplementation of Oestradiol

A

• osteoporosis
• cardiovascular disease
• side-effects of oestrogen therapy (HRT)

21
Q

What is HRT

A

• oestrogen+progestogen (to reduce proliferative effects of oestradiol on uterus)