Menstrual cycle Flashcards

1
Q

What is the purpose of the menstrual cycle?

A
  • Generate oocyte
  • facilitate fertilisation
  • optimise endometrium for implantation
  • protect developing embryo
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2
Q

When does it begin?

A

Menarche

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3
Q

When does it end?

A

menopause

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4
Q

What does the hypothalamus secrete?

A

GnRH (Gonadotropin releasing hormone)

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5
Q

What does anterior pituitary secrete?

A

FSH and LH

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6
Q

What does ovary secrete?

A

Oesttrogen

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7
Q

what kind of peptide is GnRH

A

Decapeptide

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8
Q

What is the GNRH secreted by?

A

Mid basal hypothalamic neurons

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9
Q

How is GnRH transported to pituitary?

A

Via hypophyseal portal blood system

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10
Q

What cells in the anterior pituitary secrete FSH and LH

A

Basophils

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11
Q

What does FSH do?

A
Stimulates follicular activity
Promotes estradiol (form of oestrogen) production from granulosa cells
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12
Q

What does LH do?

A

Triggers release of egg from dominant follicle.
Promotes development of the corpus luteum (a hormone-secreting structure that develops in an ovary after an ovum has been discharged).
Production of progesterone

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13
Q

What is GnRH, LH and FSH production inhibited by?

A

Rising estradiol (E2) levels

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14
Q

What is the exception? When does high levels of estradiol lead to a surge in LH release?

A

Midcycle to trigger ovulation

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15
Q

Describe the stages of the follicles?

A

Primordial follicle –> Primary/preantral follicle –>secondary/antral follicle –> preovulatory follicle –> ovulation

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16
Q

How do follicles develop?

A
  • proliferation of granulosa cells: antrum develops
  • Gap junctions and cytoplasmic processes allows communication and passage of low molecular weight materials. - nutrients
  • Proliferation of thecal cells
17
Q

How is estradiol 17-B produced?

A

Androgens secreted by theca interna cells, this is then converted to estradiol 17-B in granulosa cells.

18
Q

How does ovulation occur?

A

1) High levels of oestrogens from mature follicle stimulate release of more GnRH and LH.
2) GnRH promotes release of FSH and more LH
2) LH surge brings about ovulation

19
Q

What happens after ovulation?

A

Graafian follicle becomes empty.

Granulosa cells undergo luteinisation (LH) and become corpus luteum (12d)

20
Q

What happens if no fertilisation?

A

Corpus luteum degenrates to become corpus albicans

21
Q

What is the endometrium?

A

Lining of the uterus

22
Q

What is the proliferative phase?

A

The proliferative phase is the stage of the menstrual cycle in which ovarian follicles, structures in the ovary that each contain a single egg, mature and prime themselves for ovulation.

23
Q

What happens in the proliferative phase?

A
Endometrium thickens (action of E2)
Increased stromal cells
increased glands (blood vessels)
24
Q

What is the secretory phase?

A

Following ovulation, the follicle that released the egg is transformed into a corpus luteum, a structure that produces the pregnancy hormone progesterone, which thickens the lining of the uterus in preparation for a fertilized egg to make its home there for the next nine months

25
Q

What is the main hormone of the secretory phase?

A

Progesterone

26
Q

What happens in the secretory phase?

A

Increased secretion, increased lipids and glycogen, increased blood supply, THICK endometrium

27
Q

What are the optimal conditions for implantation of fertilised egg?

A

Stable, vascular and nutrient rich

28
Q

What happens during menstruation?

A

Vasodilation

Necrotic outer layers of endometrium separate from uterus

Uterine contraction - expel contents

29
Q

What does cervix do?

A

Mucous production from columnar glands

Stringy and runny during midcycle (easier access of sperm at ovulation)

Tenacious and inelastic in luteal phase (prevents microbes)

30
Q

What does combined oral contraceptive do?

A
  • contains estradiol and progestagen
  • Inhibits GnRH/FSH/LH
  • prevents ovulation
  • thin endometrium