Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

MD3002 Week 8 > 4. Hormonal control of the menstrual cycle > Flashcards

4. Hormonal control of the menstrual cycle Flashcards

1
Q

What are the main ovarian events during the menstrual cycle?

A

Follicular phase (days 1-14)

  1. Multiple follicles develop
  2. On day 7 one follicle becomes dominant
  3. Dominant follicle matures
  4. Ovulation occurs (day 14)

Luteal phase (days 14-28)

  1. Corpus luteum functions
  2. Corpus luteum degenerates
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Name the 2 anterior pituitary gonadotropins

A

LH

FSH

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Name 2 gonadal sex hormones

A

Oestrogen

Progesterone

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

FSH hormonal pattern?

A

Increases in early part of follicular phase, then steadily decreases throughout
remainder of cycle EXCEPT small midcycle peak.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

LH hormonal pattern?

A

Constant during most of follicular phase, then large midcycle increase (LH surge) peaking ~18h before ovulation. Then rapid decrease with further slow decline during the luteal phase.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Oestrogen hormonal pattern?

A

Low and stable for 1st week, increases rapidly in 2nd weeks, starts to decline before LH peak. Then second increase due to corpus luteum in last few days of cycle.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Progesterone hormonal pattern?

A

Low level due to ovary release during follicular phase with small increase just before ovulation. Soon a[er ovulation, large increase due to CL release, then similar paPern to oestrogen.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Inhibit hormonal pattern?

A

Similar pattern to oestrogen ie increases in late follicular phase, remains high during luteal phase, decreases as corpus luteum degenerates.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Feedback effects of ovarian hormones?

A
  1. Oestrogen, in low plasma concentrations, causes the anterior pituitary to secrete less FSH & LH in response to GnRH and also may inhibit the hypothalamic neurons that secrete GnRH.
    RESULT: -ve feedback inhibition of FSH & LH secretion during the early and middle follicular phase.
  2. Inhibin acts on the pituitary to inhibit the secre?on of FSH.
    RESULT: -ve feedback inhibition of FSH secretion throughout the cycle.
  3. Oestrogen, when increasing dramatically, causes anterior pituitary cells to secrete more LH &FSH in response to GnRH. Oestrogen can also s?mulate the hypothalamic neurons that secrete GnRH.
    RESULT: +ve feedback s?mula?on of the LH surge, which triggers ovula?on.
  4. High plasma concentra?ons of progesterone, in the presence of oestrogen, inhibit the hypothalamic neurons that secrete GnRH.
    RESULT: -ve feedback inhibi?on of FSH & LH secre?on and preven?on of LH surges during the luteal phase and pregnancy.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Role of FSH?

A

During first week of follicular phase it stimulates the growth of medium sized follicles.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Which cells express FSH receptors?

A

Granulosa cells of the ovary express FSH receptors during the follicular phase of the menstrual cycle. These cells are homologous to the Sertoli cells of the testis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Role of LH?

A

During the secretory phase it stimulates steroid hormone synthesis by the corpus luteum.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What stimulates the LH peak 12hrs before ovulation?

A

Increasing rate of secretion of oestrodiol-17beta

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Role of LH and FSH in control of oestrogen synthesis during the early and middle follicular phases?

A

LH stimulate theca cells of ovarian follicle
FSH stimulate granulosa cells of the ovarian follicle.
Theca cells: Synthesise androgens
Granulosa cells: Convert androgens (diffused from theca cells through BM) to oestrogen. Also secretes inhibin
(Main androgen is androstenedione)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What events leads to the LH surge?

A
  1. Dominant follicle release large amounts of oestrogen
  2. Oestrogen stimulates:
    -Hypothalamus to secrete GnRH
    -Ant pituitary to secrete LH (GnRH also does this)
  3. LH surge
    Lead to ovulation and follicle remnant to form CL (produces progesterone and oestrogen)
    LH action are mediated by the granulosa cells
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is the secretion regulation of oestrogen?

A

By interrelated feedback loops
There is a mid-cyme shift form -ve to +ve feedback. Leads to:
-Caused by upregulation of receptors (e.g. GnRH from hypothalamus in ant pituitary) when oestrogen levels are increased
-Results in LH and FSH surge prior to ovulation.

17
Q

Effects of LH surge on ovarian function:

  1. Meisosis and cytoplasm
  2. Antrum/blood
  3. Hormone release
  4. Follicular-ovarian membranes
  5. CL
A
  1. Primary oocyte completes its first meiotic division and undergoes cytoplasmic changes that prepare the ovum for implantation should fertilisation occur. Changes are mediated by messengers released from the granulosa cells (in response to LH)
  2. Antrum size (fluid volume) and blood flow to the follicle increase markedly.
  3. The granulosa cells begin releasing progesterone and decreasing the release of oestrogen, which accounts for the midcycle decrease in plasma oestrogen concentration and the small rise in plasma progesterone just before ovulation.
  4. Enzymes and prostaglandins, synthesized by the granulosa cells, breakdown the follicular-ovarian membranes. These weakened membranes rupture, allowing the oocyte and its surrounding granulosa cells to be carried into the surface of the ovary.
  5. The remaining granulosa cells of the ruptured follicle (along with the theca cells of that follicle) are transformed into the corpus luteum, which begins to release progesterone and oestrogen.
18
Q

7 functions of granulosa cells?

A
  1. Nourish oocyte.
  2. Secrete chemical messengers that influence the oocyte and theca
    cells.
  3. Secrete antral fluid.
  4. Are the site of action for oestrogen and FSH in the control of the follicle development during early and middle follicular phases.
  5. Express aromatase, which converts androgen (from theca cells) to oestrogen.
  6. Secrete inhibin, which inhibits FSH secretion via an action on the pituitary.
  7. Are the site of action for LH induction of changes in the oocyte and follicle culminating in ovulation and formation of the corpus luteum.
19
Q

Changes of LH and FSH in luteal phase?

A

Suppression of LH and FSH in luteal phase. (Due to -ve feedback of prog + oestr + inhibin on ant pituitary, which secretes LH and FSH)
If no implantation occurs:
-hCG does not appear in blood
-CL dies
-Progesterone and oestrogen decrease
-Menstruation occurs and next menstrual cycle begins

20
Q

How is ovulation prevented in pregnancy?

A

When progesterone levels remain high due to release from CL.
Levels of LH and FSH will be suppressed and ovulation will not occur.
In pregnancy, the human chorionic gonadotrophin produced by the placenta maintains the CL.

21
Q

What hormone is exploited therapeutically in the contraceptive pill?

A

Oestrogen. Suppresses LH and FSH which prevents ovulation

22
Q

What does oestrogen stimulate to growth?

A
  • Ovary and follicles
  • Smooth muscle and proliferation of epithelial linings of reproductive tract
  • External genitalia (esp in puberty)
  • Breasts esp ducts and fat deposition in puberty
  • Bones and also ultimate cessation of bone growth (closure of epiphyseal plates), protects against osteoporosis
23
Q

Effect of oestrogen on Fallopian tubes?

A

Increases contrac?ons and ciliary activity.

24
Q

Effect of oestrogen on uterus?

A

Increases myometrial contractions and responsiveness to oxytocin.
Stimulates secretion of abundant, watery cervical mucus.
Prepares endometrium for progesterone’s actions by inducing progesterone receptors.

25
Q

Effect of oestrogen on vagina?

A

Increases layering of epithelial cells.

26
Q

Effect of oestrogen on females body configuration?

A

Narrow shoulders, broad hips, female fat distribution (deposition on hips and breasts).

27
Q

Effects of oestrogen on skin glands?

A

Stimulates fluid secretion from sebaceous glands

28
Q

Effect of oestrogen prolactin?

A

Stimulates secretion but inhibits prolactin’s milk inducing action on the breasts

29
Q

Effect of progesterone on:

  • endometrium?
  • Mucus?
  • Contractions in Fallopian tubes?
  • Vaginal epithelium?
  • Breast growth?
  • Prolactin?
  • Hypothalamus?
  • Body temp?
A
  1. Converts the oestrogen-primed endometrium to an actively secreting tissue suitable for implanta?on of an embryo.
  2. Induces thick, sticky cervical mucus.
  3. Decreases contractions of fallopian tubes and
    endometrium.
  4. Decreases proliferation of vaginal epithelial cells.
  5. Stimulates breast growth, particularly glandular tissue.
  6. Inhibits milk-inducing effects of prolactin.
  7. Has feedback effects on hypothalamus and anterior pituitary
  8. Increases body temperature.

MD3002 Week 8 (13 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions