The Menstrual Cycle Flashcards Preview

𝚙𝚑𝚢𝚜𝚒𝚘𝚕𝚘𝚐𝚢 𝟸 : 𝚛𝚎𝚙𝚛𝚘𝚍𝚞𝚌𝚝𝚒𝚘𝚗 > The Menstrual Cycle > Flashcards

Flashcards in The Menstrual Cycle Deck (30)
Loading flashcards...
1

What kind of secretion of GnRH does there have to be?

→ pulsatile

2

What does the antral follicle produce and what does this do?

→ Estrogen
→ Progesterone
→ feedsback to hypothalamus and pituitary

3

What is the first day of the menstrual cycle?

→ The first day that bleeding occurs

4

What is the length of an ideal menstrual cycle?

→ 28 days

5

What is the follicular phase?

→ Growth of follicles until ovulation

6

What is the main hormone in the follicular phase?

→ Estrogen

7

What happens to the follicle after ovulation?

→ It becomes the corpus luteum

8

What does the corpus luteum produce?

→ Progesterone

9

What kind of feedback does progesterone have?

→ negative

10

Describe the hypothalamic/ovarian axis

1) Progesterone produced from the corpus luteum exerts negative feedback on the hypothalamus
2) If there is no pregnancy the CL dies and progesterone levels drop - no negative feedback
3) FSH levels rise again - intercycle rise in FSH
4) the early antral follicles respond to FSH and grow again
5) the follicles are producing estrogen
6) This exerts a negative feedback and FSH drops
7) the antral follicles start to die except the dominant one
8) the dominant follicle grows exponentially and produces a lot of estrogen
9) Estrogen levels are sustained for 48 hours over 300pmol
10) there is positive feedback which results in a big increase in LH but not FSH because the dominant follicle produces inhibin which inhibits FSH
11) complettion of Meiosis I and entry into meiosis II
12) LH produces proteases which 'cut' the oocyte out and cause it to be ovulated
13) It also triggers luteinization
14) CL produces progesterone

11

Why is the intercycle rise and fall in FSH important?

→ It allows the selection of a single follicle

12

What is the rise in FSH for?

→ Selection of antral follicles

13

What is the drop in FSH for?

→ The dominant follicle survives and the others die off

14

What type of growth occurs consistently?

→ Pre antral growth

15

What kind of follicles need FSH to grow?

→ follicles that have an antrum

16

What is the FSH threshold hypothesis?

→ One follicle from the group of antral follicles is at the right stage at the right time
→ It has the most number of FSH receptors
→ It becomes the dominant follicle which goes on to ovulate

17

Describe how the dominant follicle survives the fall in FSH?

→ The gene which produces the LH receptor is switched on
→ Follicle responds to LH
→ increases FSH receptors so it is responsive to falling levels of FSH
→ increases the number of granulosa cells

18

What receptors do theca cells have?

→ LH receptors

19

What do theca cells produce?

→ androgen
→ progesterons

20

What is the pathway to make estrogen?

Acetate

Cholesterol

Pregneneolone

progesterone

testosterone/androstenedione

Estrogens

21

What are the three things that can affect the hypothalamic axis?

→ Stress
→ hyperinsulinemia
→ Adipocytes

22

Why are estrogen levels raised at the end of the follicular phase?

→ The dominant follicle produces a lot of estrogen

23

What does the raised estrogen level (produced by the dominant follicle) cause?

→ Estrogen feedback switches from - to +
→ Massive release of LH from the pituitary
→ triggers ovulation

24

Describe ovulation

→ Blood flow to the follicle increases
→ Increase in vascular permeability which increases intra-follicular pressure
→ stigma on the ovary wall
→ local release of proteases
→ A hole appears in the ovary wall and ovulation occurs

25

What happens to the egg after ovulation?

→ Collected by the fimbria
→ progresses down the tube by peristalsis and action of cilia

26

What is the advantage of remaining in meiosis I ?

→ Permits the oocyte to retain all of the DNA and remain as large as possible

27

What happens to the chromosomes when the egg becomes a secondary oocyte?

→ 1/2 the chromosomes are put in a small package in the egg called the 1st polar body

28

If pregnancy occurs what is the CL supported by?

→ LH
→ HcG

29

What are the functions of progesterone?

→ Alters secretions in cervix
→ Prepares endometrium

30

What is the lifespan of the CL?

→ 14 days