Hypothalamic-Pituitary Axis and The Menstrual Cycle Flashcards Preview

Endocrine- Sex Hormones > Hypothalamic-Pituitary Axis and The Menstrual Cycle > Flashcards

Flashcards in Hypothalamic-Pituitary Axis and The Menstrual Cycle Deck (55)
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1

What 2 hormones are secreted from the anterior pituitary gland in this axis?

LH and FSH

2

How are LH and FSH secreted? In response to what?

In pulses, in response to GnRH from the hypothalamus

3

What 2 hormones exert negative feedback on LH secretion and have multiple peripheral effects?

Testosterone and oestrogen

4

What exerts negative feedback on FSH secretion?

Inhibin

5

What is the function of LH in males? Where does it exert its action?

Production of testosterone from the Leydig cells of the testes

6

What type of receptor does testosterone act on?

Nuclear androgen receptors

7

What are the roles of testosterone once it has bound to its receptor?

Male secondary sex characteristics, anabolism, maintenance of libido, aids spermatogenesis

8

Testosterone circulates, mainly bound to what?

Sex-hormone binding globulin

9

Testosterone feeds back to inhibit secretion of what?

GnRH and LH

10

Where does FSH act in males?

Sertoli cells (spermatogenic) in the seminiferous tubules

11

What is the action of FSH at the Sertoli cells?

To produce mature sperm and produce inhibins A and B

12

What is the function of inhibin?

Feeds back to the anterior pituitary to decrease FSH production

13

What peptide counteracts inhibin?

Activin

14

From where exactly in the hypothalamus is GnRH released?

Arcuate nucleus

15

Describe the production of GnRH from the hypothalamus in an adult female?

A menstrual cycle of 28 days upon the activity of GnRH. Pulses are released at about 2 hour intervals.

16

Where does LH act in a female?

Theca cells

17

Where does FSH act in a female?

Granulosa cells

18

What is the function of LH in a female?

Stimulates ovarian androgen production (at the theca cells)

19

What has to occur for ovarian androgen production to occur?

ATP - cAMP

20

What are the 3 functions of FSH in a female?

Stimulate follicular development and activity of aromatase. Also stimulates release of inhibin from ovarian stromal cells.

21

What is aromatase?

An enzyme required to convert androgens to oestrogens

22

What must occur for aromatase to be produced?

ATP - cAMP

23

What hormone and enzyme mix to produce oestrogen?

Aromatase and androgen

24

What chemical is the basis needed to produce oestrogen?

Cholesterol

25

What is cholesterol converted to in the cycle to produce oestrogen?

Pregnenolone and then progesterone

26

What exhibits a) positive feedback and b) negative feedback, on the change from pregnenolone to progesterone?

a) Inhibin (+), b) Activin (-)

27

What is progesterone converted into which can finally be converted to oestrogen?

Androstenedione

28

What exerts positive feedback on the conversion of androstenedione to oestrogen?

Activin

29

When in the menstrual cycle does ovulation usually occur?

Day 14

30

The follicular stage of the menstrual cycle begins when oestrogen levels are?

Low

31

What stimulates the follicle to develop in the follicular stage of the menstrual cycle?

FSH

32

What happens to the granulosa cells around the egg in the follicular stage of the menstrual cycle?

They enlarge, releasing oestrogen

33

What does the increased oestrogen by the end of the follicular stage of the menstrual cycle do?

Causes thickening of the uterine lining

34

What hormone level peaks at the beginning of the follicular stage of the menstrual cycle?

FSH

35

What happens to oestrogen levels in the follicular stage of the menstrual cycle?

They start low and are raised at the end

36

What is the relative concentration of progesterone throughout the follicular stage of the menstrual cycle?

Low

37

When does ovulation occur?

At the peak of follicular growth, in response to an LH surge

38

What happens after the LH peak in the ovulation stage of the menstrual cycle?

The oocyte is released into the ampulla of the fallopian tube

39

What hormone has a large peak at the beginning of ovulation?

LH

40

What hormone has a small peak at the beginning of ovulation?

FSH

41

In the luteal phase of the menstrual cycle, why are the remaining granulosa cells around the egg yellow?

They absorb a lot of keratin

42

What are the remaining granulosa cells known as in the luteal phase?

Corpus luteum

43

What hormone does the corpus luteum secrete?

Progesterone

44

When is there a peak of oestrogen in the luteal phase?

First 1/3rd of the phase

45

What is the major hormone of the luteal phase?

Progesterone

46

What hormones are responsible for endometrial proliferation in preparation for implantation?

Oestrogen initially and then progesterone

47

If implantation does not occur, what happens to the corpus luteum?

It regresses, so progesterone and inhibin levels fall so that the endometrium is shed

48

What hormones are increased again if no pregnancy occurs at the end of a menstrual cycle?

GnRH and FSH

49

What hormone will be produced at the end of the menstrual cycle if a pregnancy has occurred?

HCG

50

How is the ovary attached to the pelvic side wall?

Infundibulopelvic ligament

51

What are the two parts of an ovary? Which contains the follicles?

Outer cortex and inner medulla, the cortex contains the follicles

52

What components make up the uterus?

Body of the uterus and cervix

53

Oestrogen acts synergistically with what other hormone?

FSH

54

Where can oestrogen be synthesised?

Ovaries, but also adrenal glands, fat and bone

55

What are both inhibin and activin and where are they found?

Peptides in follicular fluid