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HUBS192 Missing Cards > Lecture 37: Female reproductive system 2 > Flashcards

Lecture 37: Female reproductive system 2 Flashcards

1
Q

what is oogenesis?

A

formation and development of the oocyte from oogonia

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2
Q

what does oogenesis require?

A

mitosis and meiosis

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3
Q

what happens to gametes before birth?

A

lifetime supply of gametes produced before birth

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4
Q

when does oogenesis happen?

A
  • initiate before birth
  • continues between puberty and menopause
  • it is cyclic so there is 1 ovulation every 28 days (average)
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5
Q

where do oocytes develop?

A

oocytes develop within ovarian follicles
- 1 oocyte per follicle

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6
Q

what part of oogenesis occurs before birth?

A
  • oogonium (diploid) in the gonad
  • population of oogonia increases by mitosis (this stops before birth)
  • oogonia differentiate to form primary oocytes (diploid)
  • primary oocytes are encased in primordial follicle
  • many primary oocytes undergo atresia
  • the primary oocytes start meiosis
  • meiosis halts at prophase 1
  • stops here until puberty begins
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7
Q

what happens when oogenesis resumes at puberty?

A
  • at puberty, females have 300,000 oocytes
  • under GnRH influence, a small number of follicle are recruited each ovarian/menstrual cycle
  • only 1 oocyte will complete development and ovulate (within dominant follicle)
  • primary oocyte completes meiosis 1.
  • it forms a secondary oocyte and 1st polar body (both are haploid)
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8
Q

what happens after the secondary oocyte is formed?

A
  • the secondary oocyte starts meiosis 2
  • it halts at metaphase 2
  • stops until fertilisation occurs
  • meiosis 2 resumes when the sperm penetrates the plasma membrane of the ovum at fertilisation
  • if not fertilised, it will degenerate through a process called atresia and never complete meiosis
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9
Q

what are the features of the follicles during oogenesis?

A
  • oocyte develops within a developing follicle
  • follicle are multilayered with granulosa cells and theca cells
  • granulosa cells produce estradiol
  • when ovulation occurs, the oocyte and corona radiata are released into the peritoneal cavity
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10
Q

what are the female reproductive hormones? what are the released by?

A
  • GnRH (hypothalamus)
  • FSH (anterior pituitary)
  • LH (anterior pituitary)
  • estradiol (ovary follicles)
  • inhibin (ovary follicle and corpus luteum)
  • progesterone (corpus leuteum)
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11
Q

what does GnRH stimulate in the female reproductive system?

A
  • released in hypothalamus
  • release of FSH and LH
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12
Q

what does FSH stimulate in the female reproductive system?

A
  • released from anterior pituitary
  • stimulates growth of ovarian follicles
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13
Q

what does LH stimulate in the female reproductive system?

A
  • released from anterior pituitary
  • surge of LH in ovulation
  • formation of corpus luteum
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14
Q

what does estradiol stimulate in the female reproductive system?

A
  • found in developing follicles
  • assists follicle growth with FSH
  • bone and muscle growth
  • endometrial growth
  • secondary sex characteristics
  • feedback to anterior pituitary
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15
Q

what does inhibin stimulate in the female reproductive system?

A

negative feedback to anterior pituitary to suppress FSH

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16
Q

what does progesterone stimulate in the female reproductive system?

A
  • released from corpus luteum
  • negatively feeds back to suppress GnRH (therefore LH and FSH)
  • endometrial maturation
  • maintains pregnant state
17
Q

what is the ovarian/menstrual cycle?

A
  • the regular cyclic changes in the ovary and uterus that prepares an oocyte/ova for fertilisation and the endometrium from embryo implantation
18
Q

when do the menstrual cycles occur?

A

on an approximate monthly basis (28 days) between menarche and menopause

19
Q

what is menarche?

A
  • first menstrual period
  • occurs at age 12-13 on average
  • part of puberty orchestrated by increase in sex steroid production (estrogens) by the gonads
20
Q

what is menopause?

A
  • cessation of menstruation
  • reduction of estradiol and progesterone due to absence of or lack of response by follicles
  • anterior pituitary feedback no longer active, therefor FSH and LH is high
21
Q

what are the 2 ovarian cycles?

A
  • follicular (preovulatory phase)
  • luteal (postovulatory phase)
22
Q

when does the follicular (preovulatory) phase occur?

A

Day 1-14

23
Q

when does the luteal (postovulatory) phase occur?

A

day 15-28

24
Q

what happens in the follicular (preovulatory phase)

A
  • increased FSH from anterior pituitary
  • this stimulates follicular growth
  • the growing follicle secrete estradiol and inhibin
  • this reduces FSH from anterior pituitary by negative feedback
  • growing follicles undergo atresia, except the dominant follicle
  • the dominant follicle secretes large amounts of estradiol
  • this stimulates a surge of LH by positive feedback
  • the follicle rupture and ovulation occurs
  • the oocyte enters the peritoneal space/collected into uterine tube
25
Q

what happens in the luteal (postovulatory phase)?

A
  • ovulated follicle collapses and forms corpus luteum
  • it secrete progesterone, estradiol and inhibin
  • these decrease FSH and LH secretion by negative feedback on the hypothalamus (GnRH)
  • if fertilisation and implantation do not occur, the corpus luteum involutes (luteolysis)
  • this results in a fall in progesterone and estradiol
  • this removed negative feedback of FSH and LH and the cycle starts again
26
Q

what are the 2 menstrual cycles?

A
  • menstrual and proliferative phase
  • secretory (and premenstrual) phase
27
Q

when does the menstrual and proliferative phase occur?

A

Day 1-14

28
Q

what does the secretory (and premenstrual) phase occur?

A

Day 15-28

29
Q

what happens in the menstrual and proliferative phase?

A
  • the endometrium breaks down and bleeds during menstruation
  • estradiol stimulates endometrial growth from days 6-14
  • involves rapid tissue growth, including growth of glands and vasculature
30
Q

what happens in the secretory phase?

A
  • after ovulation (day 14), the corpus luteum secretes progesterone
  • progesterone promotes endometrial maturation
  • glands become secretory
  • spiral arterioles grow and coil
31
Q

what happens after the secretory phase if fertilisation and implantation do not occur?

A
  • corpus luteum atrophies
  • progesterone levels fall
  • spiral arteries contract
  • endometrial tissue breaks down and bleeding occurs
  • shed tissue and blood removed via cervix and vegina (menstruation)
  • cycle continues until fertilisation occurs

HUBS192 Missing Cards (31 decks)

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