Lecture 37: Female reproductive system II Flashcards

1
Q

What is Oogenesis?

A

The formation and development of the oocyte (female gamete) from oogonia

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

What is required to carry out Oogenesis?

2

A
  • Mitosis

- Meiosis

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

How many gametes are produced and when are they produced for Oogenesis?

A

A lifetime supply of gametes are produced, before birth

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

When does Oogenesis begin?

A

Before birth but then halts until puberty

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

When oogenesis begins to continue again what time period does oogenesis occur between?

A

Between puberty (Menarche) and menopause

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

Between puberty and menopause how often does oogenesis occur?

A

1 ovulation every 28 days (on average) - cyclic

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

Before birth oogonium are what?

A

Diploid (2n=46 chromosomes) in gonads

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

How does the population of oogonia increase?

A

By mitosis (which stops before birth)

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

Oogonia differentiate to form what?

A

Primary oocytes (diploid, 2n=46 chromosomes)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What are Oogonia that differentiate to form primary oocytes encased by?

A

Primordial follicle

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

What do many primary oocytes undergo?

A

Atresia

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

What happens to primary oocytes that have formed?

A

They start meiosis

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

When do primary oocytes halt in meiosis

A

Prophase 1

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

After oocytes have halted at prophase 1 of meiosis when does it begin again?

A

When puberty begins

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

At puberty approximately how many oocytes do females have?

A

300,000

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Under the influence of GnRH what happens each ovarian/menstrual cycle?

A

A small number of follicles are recruited

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

During a menstrual cycle what will happen to only one oocyte?

A

It will complete development and ovulate (within the dominant follicle)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What do primary oocytes that complete meiosis I form?

A

Secondary oocytes and 1st polar body (both haploid, n=23)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What do secondary oocytes start?

A

Meiosis II but it halts at metaphase II and is suspended until fertilisation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

When do secondary oocytes continue meiosis II?

A

They resume meiosis II when the sperm penetrates the plasma membrane of the ovum at fertilisation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What happens to secondary oocytes that are not fertilised?

A

They will degenerate (atresia) and therefore never complete meiosis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Where does oogenesis occur?

A

Within developing follicle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What are follicles?

A

Multilayered granulosa/theca cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What do granulose cells produce?

A

Estradiol

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

During ovulation what happens to the oocyte?

A

They are released into the peritoneal cavity with corona radiata

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

What does GnRH from the hypothalamus do?

A

Stimulate the release of FSH and LH

27
Q

What does FSH from the anterior pituitary stimulate in ovarian follicles?

A

The growth of ovarian follicles

28
Q

What does LH from the anterior pituitary stimulate?

A

A surge of LH involved in ovulation, formation of corpus luteum

29
Q

What does estradiol from developing
follicles assist with?
(5)

A
  • Follicle growth (with FSH)
  • Bone and muscle growth
  • Endometrial growth
  • Feedback to anterior pituitary
  • Secondary sex characteristics
30
Q

What does inhibin from granulose cells do?

A

support negative feedback to anterior pituitary to suppress FSH

31
Q

What does progesterone from the corpus luteum support?

2

A
  • Negatively feeds back to suppress GnRH (therefore LH and FSH)
  • Endometrial maturation or maintains pregnant state
32
Q

What is the ovarian/menstrual cycles?

A

The regular cyclic changes in the ovary and uterus that prepare an oocyte/ova for fertilisation and the endometrium for embryo implantation

33
Q

How often does the menstrual cycle occur?

A

Approximately monthly basis between menarche and menopause

34
Q

What is menarche?

A

The first menstrual period

35
Q

When does menarche occur?

A

At age 12-13 years on average

36
Q

Menarche is the part of puberty orchestrated by what?

A

Increase in sex steroid production (oestrogen’s) by the gonads

37
Q

What is menopause?

A

Cessation of menstruation

38
Q

When does menopause typically occur?

A

In early 50’s

39
Q

Menopause is a reduction of what in response to the absence of what?

A

The reduction of estradiol and progesterone due to the absence of or lack of response by follicles

40
Q

What are the stages of the female reproductive cycle - Ovarian?
(2)

A
  • Follicular (preovulatory phase) Day 1 - 14

- Luteal (postovulatory phase) Day 15 - 28

41
Q

What happens to FSH during the follicular phase?

A

Increased FSH from the anterior pituitary

42
Q

What does FSH from the anterior pituitary stimulate during the follicular phase?

A

Follicular growth

43
Q

What do growing follicle secrete during the follicular phase?

A

Estradiol and inhibin

44
Q

What does does estradiol and inhibin reduce during the follicular phase?

A

Reduces FSH from the anterior pituitary (negative feedback)

45
Q

What does estradiol and inhibin cause the growing follicles to do in the follicular phase?

A

Atresia, except the dominant follicle

46
Q

What does the dominant follicle secrete during the follicular phase?

A

Large amounts of estradiol

47
Q

What does high estradiol stimulate during the follicular phase?

A

It stimulates a surge of LH (positive feedback)

48
Q

During the follicular phase what happens to the dominant follicle following a surge of LH?

A

The follicle ruptures and ovulation occurs, oocytes then enters peritoneal space/collected into uterine tube

49
Q

What happens to ovulated follicle during the luteal phase?

A

Ovulated follicle collapses and forms corpus luteum which secretes progesterone, estradiol and inhibin

50
Q

What does the progesterone, estradiol and inhibin released from the ovulated follicle cause during the luteal phase?

A

They decrease FSH and LH secretion causing negative feedback on the hypothalamus

51
Q

What happens in the luteal phase if fertilisation and implantation does not occur?

A

The corpus luteum involutes (luteolysis) causing a fall in progesterone and estradiol

52
Q

What does a fall in progesterone and estradiol cause in the luteal?

A

Removal of negative feedback on FSH and LH causing the cycle to starts again

53
Q

What are the stages of the Menstrual cycle?

2

A
  • Menstrual and proliferative

- Secretory

54
Q

What happens to the endometrium during the menstrual/proliferation phase?

A

It breaks down and bleeds during menstruation

55
Q

What does estradiol stimulate?

A

Endometrial groth from approximately day 6-14

56
Q

What happens during the menstrual and proliferation phase to tissue/glands/vasculature?

A

Rapid growth

57
Q

What does the corpus luteum do during the secretory phase?

A

It secretes progesterone

58
Q

What does progesterone promote during the secretory phase?

A

Endometrial maturation where glands become secretory and spiral arterioles grow and coil

59
Q

What happens to the corpus luteum if fertilisation and implantation do not occur during the secretory phase?

A

It atrophies

60
Q

What happens to progesterone levels if fertilisation and implantation do not occur during the secretory phase?

A

The progesterone levels fall

61
Q

What happens to the spiral arteries if fertilisation and implantation do not occur during the secretory phase?

A

The spiral arteries contract

62
Q

What happens to the endometrial tissue if fertilisation and implantation do not occur during the secretory phase?

A

It breaks down and bleeding occurs

63
Q

What happens to the shed tissue and blood if fertilisation and implantation do not occur during the secretory phase?

A

It is removed via the cervix and vagina