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BIOL 112 > Lecture 17: Female Reproductive Physiology > Flashcards

Lecture 17: Female Reproductive Physiology Flashcards

1
Q

what is oogenesis

A

-Formation of gametes within the ovaries
-Begins before birth with meiosis; Accelerate at puberty; Ends at menopause
-During fetal devpt, Primordial germ cells migrate from the yolk
sac to the ovaries, and
differentiate into oogonia

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2
Q

what are the steps in oogenesis

A
  1. mitosis of oogonium (divide into 2)
  2. Meiosis I: between 3 & 7 months of fetal development the primary oocytes prepare to undergo meiosis, each month after the ovarian cycle begins some of the primary oocytes are stimulated to undergo further development, meiosis I is then completed yeilding a first polar body and a secondary oocyte
  3. Meiosis II: each month after ovarian cycle begins, one secondary oocyte leaves the ovary suspended in metaphase of meiosis II, at fertilization a second polar body forms and the fertilized secondary oocyte is then called a mature ovum
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3
Q

slide 4

A

ovarian follicles: specialized structures within cortex, growth of oocyte and meiosis I

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4
Q

slide 4

A

activated-> maturation (more components of cell are present)-> mature (more specialized cell)

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5
Q

what are the ovarian follicular stages

A

-at ovulation, both secondary oocyte, a polar body and a corona radiata are released into the pelvic cavity, and hten swept into uterine tube
-sper, presence/fertilization occurs, secondary oocyte continues into meiosis II, an ovum and a secondary polar body form, ovum becomes a zygote with its nucleus unites with that of sperm
-absence of fertilization= cells degenarate

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6
Q

review slide 6 of comparison between spermatogenesis and oogenesis

A
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7
Q

what is the female reproductive cycle (FRC)

A

-females experienced repeated. changes in ovaries and urterus per month
-involves oogenesis and uterine preparation to receive fertilized ovum

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8
Q

what does the female reproductive cycle involve

A

-ovarian cycle: changes that occur during and after maturation of the oocyte
-uterine cycle: changes in the endometrium that prepare it for implantation of the developing embryo
-hormonal changes: changes in breasts and cervix

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9
Q

what is the ovarian cycle

A

-A monthly (~28 day) series of events associated with maturation of egg
-Two consecutive phases, with ovulation occurring midcycle btw them
I. Follicular phase: period of vesicular follicle growth (days 1–14)
II. Luteal phase: period of corpus luteum activity (days 14–28)
-Only 10–15% women have 28-day cycle
-Follicular phase varies, but luteal phase is always 14 days from ovulation
to end of cycle

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10
Q

what happens in the follicular phase

A

-Graafian follicle creates bulge in ovary
-Oocyte and its follicular cells project into antrum: Surrounded by granulosa cells & Adjacent stromal cells form layer of thecal
endocrine cells that produce estrogens
-Rising LH levels prompt
completion of meiosis I
-Corona radiata formation: granulosa cells that remain
associated with secondary oocyte

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11
Q

what is ovulation

A

-Inflating ovary walls rupture, Graafian follicle releases 2o oocyte with its corona radiata into pelvic cavity
-Via ciliary action, Oocyte are swept into uterine tube by fimbriae
-1–2% of ovulations release more than one 2o oocyte, if fertilized, results in fraternal twins
-Identical twins result from fertilization of one oocyte, then separation of
daughter cells

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12
Q

what happens in the luteal phase

A

Corpus Luteum Formation:
-Forms from remaining granulosa cells under stimulation of LH
-Appears yellow in color due to cholesterol
-Cholesterol is converted to progesterone – prepares uterus for pregnancy
-Secretes moderate amounts of estrogens
-Begins degenerating ~12 days after ovulation

Corpus Albicans:
-Produced from nonfunctional corpus luteum as fibroblasts invade and form scar tissue
-Marks end of ovarian cycle

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13
Q

what is the urterine (menstrual cycle)

A

-repeating series of changes in endometrium
-lasts from 21 to 35 days. averaging 28 days
-menarche: first unterine cycle; begins at puberty (age 11 to 12)

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14
Q

what are the three phases of uterine cycle

A

menstrual, proliferative, and secretory phase
-menstrual and proliferative phases: during ovarian follicular phase
-secretpry phase: during ovarian luteal phase

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15
Q

describe the menstrual phase

A

-Degeneration of endometrial functional layer (stratum functionalis)
-Occurs in patches; Leads to menstruation
-Caused by constriction of spiral arteries
-Reducing blood flow, O2, and nutrients → weakened arterial walls → rupture →
releasing blood into CTs of functional layer
-Ovarian hormones are at the lowest

Menses
-Entire functional layer is lost through external os and vagina
-Only functional layer is affected, deeper, stratum basalis is supplied by straight arteries
-Lasts 1-5 days

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16
Q

describe the proliferativee phase

A

-Epithelial cells of uterine glands: Multiply and spread across endometrial surface & Restore integrity of uterine epithelium
-Further growth and vascularization: Completely restore stratum functionalis
-Occurs at same time as enlargement of Graafian ovarian follicles
-Stimulated and sustained by estrogens secreted by devping ovarian follicles
-Entire stratum functionalis is highly vascularized: Small arteries spiral toward inner surface

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17
Q

describe the secretory phase

A

-Uterine glands enlarge, increasing rates of secretion
-Arteries of uterine wall: Elongate and spiral through functional layer
-Begins at ovulation and persists as long as corpus luteum remains intact
-Secretion peaks about 12 days after ovulation; Generally, lasts 14 days
-Ends as corpus luteum stops producing hormones

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18
Q

how does estrogens do

A

-promote development & maintenance of female reproductive structures and secondary sex characteristics
-increase protein anabolism
-lower blood cholesterol
-stimulate proliferation of stratum basalis to form a new stratum functionalis after menstruation occurs
-moderate levels inhibit release of GnRH, FSH, and LH

19
Q

what does inhibin do

A

inhibits release of FSH (follicle stimulating hormone)

20
Q

what does relaxin do

A

-inhibits contractions of uterine smooth muscles
-during labour, increases flexibility of pubid symphysis and dilates uterine cervix

21
Q

what does progesterone do

A

-stimulates endometrial glands to secrete glycogen and lipids, which serve as an initial nutrient source for a fertilized egg
-high levels inhibit release of GnRH, FSH, and LH

22
Q

what is the female sexual response

A

-Initiated by touch and psychological stimuli
-Clitoris, vaginal mucosa, bulbs of vestibule, and breasts engorge with blood; nipples become erect
-Vestibular gland secretions lubricate vestibule

23
Q

describe the 4 phases of female sexual response cycle

A
  1. excitement phase: vasocongestion swells the vaginal tissue, the clitoris, and the area surrounding the opening of the vagina, vagina; lubrication appears, the inner two-thirds of the vagina expand and the vaginal walls thicken and turn a deeper colour
  2. plateau phase: the inner two-thirds of the vagina fully expand, the outer third of the vagina thickens, the clitoris retracts behing its hood and the uterus elevates and increases in size
  3. orgasm phase: contractions of the pelvic muscles surrouding the vagina occur
  4. resolution phase: multiple orgasms may occur if the woman desires it and sexual stimulation continues
24
Q

what is the female orgasm accompanied by

A

-Peristaltic contractions of uterine and vaginal walls
-Rhythmic contractions of bulbospongiosus and ischiocavernosus muscles
-Increase in pulse rate and BP
-Females have no refractory period after orgasm; can experience multiple orgasms in single sexual experience

25
Q

describe fertilization

A

-Fertilization: sperm’s chromosomes combine with those of secondary oocyte to form fertilized egg, called a zygote
Before fertilization can occur, sperm must reach secondary oocyte
-Oocyte viable for 12 – 24 hours
-Sperm viable 24 – ~72 hours after ejaculation
-For fertilization to occur, coitus (sex) must occur no more than 2 days before and at least 24 hours after ovulation

26
Q

describe sperm transport and capacitation

A

-Capacitation before Penetration into Oocyte: Motility must be enhanced, and cell membranes must become fragile enough to release hydrolytic enzymes
-Secretions of female tract help to weaken and thin out acrosome membrane
-Sperm have olfactory receptors that follow chemical trail released by egg or surrounding cells
-Sperm “sniff” their way to oocyte

27
Q

what are the steps in acrosomal reaction and sperm penetration

A
  1. approach: acrosome releases enzymes
  2. acrosomal reaction: oocyte and sperm plasma membranes fuse
  3. granules release enzymes that make the zona pellucida impenetrable
  4. binding & fusion: sperma nucleus engulfed by oocyte cytoplasm
28
Q

what are the steps in conception

A
  1. ovulation 2. fertilization 3. cleavage 4. cleavage 5. implantation
    -Fertilization of an egg by a sperm, occurs in the oviduct
    -The resulting zygote begins to divide by mitosis in a process called cleavage
    -Division of cells gives rise to a blastocyst, a ball of cells with a central cavity
    -After blastocyst formation, embryo implants into the endometrium
29
Q

describe how urine shows pregnant on pregnancy tests

A

-The embryo releases human chorionic gonadotropin (hCG) → prevents menstruation
* Some hCG passes into the urine, where it can be
detected by early pregnancy tests

30
Q

what is pregancy or gestation

A

it is the condition of carrying one or more embryos in the urterus
-average 266 days (38 weeks, ~ 9 months) in humans, divided into three equal trimesters

31
Q

describe the first trimester

A

-Time of most radical change for both mother and embryo
-Implanted embryo secretes hormones that regulate the mother’s reproductive system
-One such hormone, human chorionic gonadotropin (hCG) maintains secretion of progesterone and estrogens during early pregnancy
-During first 2-4 wks, the embryo obtains nutrients directly from endometrium
-Meanwhile, the outer layer of blastocyst, the trophoblast, mingles with the endometrium and eventually forms the placenta
-Blood is carried from embryo to placenta and vice versa through umbilical vessels

32
Q

what is organogenesis and what does it occur

A

the first trimester is main period of organogenesis, development of the body organs
-all major structures are present by week 8, and the embryo is called a fetus

33
Q

what changes occur in a mother in the first trimester

A

-Mucus plug to protect against infection
-Growth of the placenta and uterus
-Cessation of ovulation and the menstrual cycle
-Breast enlargement
-Nausea is also very common

34
Q

what happens in the second trimester

A

-the fetus grows and is very active
-the mother may feel fetal movements
-the uterus grows enough for the pregnancy to become obvious

35
Q

what happens in the thrid trimester

A

the fetus grows and fills the space within the embryonic membranes

36
Q

what happens in labour

A

a series of strong, rhythmic uterine contractions that push the fetus & placenta out of the body
-regulated by prostaglandins and hormones: estradiol & oxytocin

37
Q

what are the three stages of labour

A

a) Thinning and opening, or dilation, of the cervix
b) Expulsion or delivery of the baby
c) Delivery of the placenta
* Postnatal care in mammals includes lactation, the production of milk

38
Q

describe the positive feedback system in labour

A
  1. estradiol from the ovaries activates oxytocin receptors on uterus
  2. oxytocin from fetus and mother’s posterior pituitary: stimulates the uterus to contract with stimulates more oxytocin production & the oxytocin also stimulates the placenta to make prostaglandins which stimulates more contractions of the uterus
39
Q

what are some contraceptions methods

A
  • Abstinence
  • Barrier methods
  • Intrauterine devices
  • Chemical and surgical methods
40
Q

review slide 31

A
41
Q

review slide 32

A
42
Q

what is amenorrhea

A

absence of menstruation
-primary amenorrhea: failure ot initiate menstruation
-secondary amenorrhea: transient, interruption of 6 months or more, caused by several factors including drastic weight loss and emotional stress

43
Q

list some other conditions associated with menstruation

A

-dysmenorrhea: very painful menstruation
-oligomenorrhea: abnormally infrequent and scanty menstrual flow
-polymenorrhea: menstruation at abnormally frequent intervals

44
Q

how can extremely strenuous physical activity delay menarche in girls

A
  • Can cause amenorrhea, cessation of menstruation
  • Female athletes have little body fat; adipose cells are needed to convert adrenal androgens to estrogens and produce leptin that plays role in puberty
  • Lack of leptin can shut down reproductive cycles
  • Can reverse if woman increases body fat

BIOL 112 (21 decks)

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