2.2 The Menstrual Cycle Flashcards Preview

Semester 4- Reproduction > 2.2 The Menstrual Cycle > Flashcards

Flashcards in 2.2 The Menstrual Cycle Deck (12)
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1
Q

What are the levels of FSH and LH like at the start of the menstrual cycle?

A

Low as there is no ovarian hormone production as the follicle is developing

2
Q

Why do FSH levels rise early in the menstrual cycle?

A

Little inhibition at the anterior pituitary or hypothalamus. Little inhibin production

3
Q

Where does the FSH bind to in the early menstrual cycle and what does this result in?

A

Binds to the granulosa cells

Aids follicular development so follicle can now produce oestrogen and inhibin

4
Q

In the mid-follicular phase of development what affect does low oestrogen have on the anterior pituitary and hypothalamus?

A

Increases secretion of LH and FSH by negative feedback

5
Q

Why in the mid-follicular phase of the menstrual cycle do LH levels rise but not FSH levels?

A

Inhibin release from the ovary is inhibiting FSH production

6
Q

How does the body prepare for ovulation?

A

Oestradiol and inhibin rise rapidly
Progesterone production begins
Follicle cells respond to LH

7
Q

What causes the surge in LH before ovulation?

A

Oestradiol is not dependent on FSH levels so LH levels surge

8
Q

What happens in ovulation?

A

Meiosis I completes and meiosis II starts. Mature oocyte extruded through the capsule of the ovary

9
Q

After ovulation how are LH levels reduced?

A

Large progesterone release from the corpus luteum decrease the oestrogen to progesterone ratio.
LH is suppressed by negative feebdack to the anterior pituitary and hypothalamus

10
Q

What happens in the luteal phase of menstruation?

A

Corpus luteum produces progesterone, oestrogen and inhibin and waiting phase is started

11
Q

What happens to the menstrual cycle if no fertilisation occurs?

A

Cycle starts again

Corpus luteum degenerates and hormone levels are decreased.

12
Q

How long is a normal menstrual cycle?

A

21-35 days

Luteal phase is always 14 +/- 2 days