HUBS192 Lecture 37 - Female Reproductive System II Flashcards
what are the layers of the uterine wall from outermost to innermost?
1) perimetrium
2) myometrium
3) endometrium
what layer of the uterine wall is shed during menstruation?
endometrium layer
which artery associated with the female reproductive tract branches directly off the abdominal aorta?
the ovarian artery
which ligament does the ovarian artery run through?
runs thought the suspensory ligament
what is the name of the fingerlike projections on the infundibulum?
fimbriae
what is oogenesis?
formation and development of the oocyte (female gamete) from oogonia
what does oogenesis require to occur?
requires mitosis and meiosis
when is the lifetime supply of gametes produced?
lifetime supply of gametes produced before birth
when is oogenesis initiated?
initiated before birth
when does oogenesis continue between?
continues between puberty and menopause
what is the pattern of oogenesis?
cyclic
what is the average number of days for 1 ovulation?
1 ovulation every 28 days on average
where do oocytes develop?
develop within the ovarian follicles
how many oocytes develop per follicle?
1 oocyte develops per follicle
when do follicles grow and mature?
follicles grow and mature prior to ovulation
what is the relationship between a developing oocyte and a developing follicle?
follicles develop at the same time as the developing oocyte
what does the follicle differentiate into?
goes on to differentiate and form the corpus lutem
how many ovum will you end up with at the end of oogenesis?
only ever end up with 1 ovum
what is an oogonium?
an immature diploid female reproductive cell that gives rise to primary oocytes by mitosis
how does the population of oogonia increase?
increase by mitosis
what do oogonia differentiate to form?
differentiate to form primary oocytes that are diploid (2n = 46)
what are primary oocytes encased in?
encased in primordial follicles
-one primordial follicle per encases one primary oocyte
what do many primary oocytes undergo?
many primary oocytes undergo atresia
how many primary oocytes is a female born with?
around 700,000
what number will the primary oocytes decease to by puberty?
around 300,000
what are primary oocytes surrounded by?
surrounded by the first layer of follicular cells
when do primary oocytes start developing?
start in meiosis
what stage of meiosis does primary oocytes halt and when? (in terms of age)
meiosis halts at prophase I and halts until puberty begins
what is menarche?
the first menstrual cycle
under what hormonal influence are a small number of follicles recruited for each ovarian/menstrual cycle?
under the influence of GnRH
what is a primary oocyte?
the only 1 oocyte that has completed development and ovulation with the dominant follicle
what does the primary oocyte complete in terms of meiosis?
primary oocyte complete meiosis I
what does the primary oocyte form after the completion of meiosis I?
forms a secondary oocyte and the 1st polar body
-both haploid (n=23)
what is the 1st polar body?
the uneven genetic division of cytoplasm that results in 1 of the 2 daughter cell containing more cytoplasm than its counterpart
does the primary or the secondary oocyte start meiosis II?
the secondary oocyte starts meiosis II
when does the secondary oocyte halt in meiosis?
halts at metaphase II
why does the secondary oocyte halt at metaphase II?
suspends until fertilisation
when does meiosis II resume?
resumes when the sperm penetrates the plasma membrane of the ovum at fertilisation
what will happen to the secondary oocyte if it is not fertilised?
if not fertilised, the secondary oocyte will degenerate (atresia) and therefore will never complete meiosis
what happens to unfertilised oocytes?
unfertilised oocytes undergo atresia and degenerate
what is a fertilised ova?
a zygote
is a fertilised ova (zygote) haploid or diploid?
diploid, 2n=46
what does a primary oocyte form?
forms a secondary oocyte and a polar body
what is a primordial follicle?
a follicle that encloses that each primary oocyte
what is the the relationship between different types of follicles and oocytes?
even tertiary follicles will still contain a primary oocyte
what are the 2 cells that compose the multilayered follicles?
1) granulosa cells
2) theca cells
what do granulosa cells produce?
produce estradiol
what are the 6 female reproductive hormones?
1) GnRH (Gonadotrophin Releasing Hormone)
2) FSH (Follicle Stimulation Hormone)
3) LH (Luteinising Hormone)
4) Estradiol (an estrogen)
5) Inhibin
6) Progesterone
where is GnRH (gonadotrophin releasing hormone) produced in?
produced in the hypothalamus
where is FSH (follicle stimulating hormone) produced in?
in the anterior pituitary
where is LH (luteinizing hormone) produced in?
produced in the anterior pituitary
where is estradiol (an estrogen) and inhibin produced in?
produced in the ovary in the follicles
where is inhibin, progesterone and estradiol (an estrogen) produced in?
produced in the ovary in the corpus luteum
what hormone does the hypothalamus produce?
GnRH (gonadotrophin releasing hormone)
what hormones does the anterior pituitary produce?
FSH (follicle stimulating hormone)
LH (luteinizing hormone)
what hormones does the ovary follicles produce?
estradiol (an estrogen)
inhibin
what hormones does the ovary corpus luteum produce?
inhibin
progesterone
estradiol (an estrogen)
what is estrogen?
a group of steroid hormones
what is estradiol an example of?
an example of a single hormone
what is the effect of GnRH released from the hypothalamus?
releases FSH (follicle stimulating hormone) and LH (lutenizing hormone)
what is the effect of FSH released from the anterior pituitary?
stimulates the growth of ovarian follicles
what is the effect of LH released from the anterior pituitary?
- surge of LH involved in ovulation
- formation of corpus luteum
what is the effect of estradiol released from the developing follicles?
- assists in follicle growth with FSH
- bone and muscle growth
- endometrial growth
- secondary sex characteristics
- feedback to the anterior pituitary
what is the effect of inhibin released from the granulosa cells?
negative feedback tot he anterior pituitary to suppress FSH (follicle stimulating hormone)
what is the effect of inhibin released from the corpus luteum?
- negatively feeds back to suppress GnRH therefore LH and FSH
- endometrial maturation by preparing the endometrium for implantation
- maintains pregnant state
what are ovarian/menstrual cycles?
the regular cyclic changes in the ovary and uterus that prepare an oocyte/ova for fertilisation and the endometrium for embryo implantation
what is menarche?
the first menstrual period
when does menarche occur?
occurs at age 12-13 years old on average
what is menarche orchestrated by?
orchestrated by increase in sex steroid production (estrogen’s) by the gonads
what is menopause?
the cessation of menstruation
when does menopause typically occur?
typically occurs in the early 50s
why does menopause occur?
because of the reduction of estradiol and progesterone due to the absense of or lack of response by follicles
what is no longer active during menopause? (in terms of regulation)
anterior pituitary feedback is no longer active leading to high levels of FSH and LH
what does menopause cause a reduction of?
reduction in primordial oocytes
what occurs in the follicular (preovulatory) phase from days 1 to 14?
- increased FSH (follicle stimulating hormone) from the anterior pituitary stimulate follicular growth
- growing follicles secrete estradiol and inhibin and this reduces FSH from the anterior pituitary and through negative feedback and growing follicles undergo atresia except the dominant follicle
- dominant follicle secretes large amounts of estradiol
- high estradiol stimulates surge of LH through positive feedback
- follicle ruptures and ovulation occurs as the oocyte entering the peritoneal space and is collected in the uterine tube
is the surge of LH controlled by negative or positive feedback?
positive feedback
what occurs in the luteal (postovulatory) phase from days 15 to 28?
-ovulated follicle collapses and forms the corpus luteum which secretes progesterone, estradiol and inhibin which decrease the FSH and LH secretion by negative feedback from the
hypothalamus
what happens if fertilisation and implantation does not occur in the luteal (postovulatory) phase from days 15-28?
if fertilisation and implantation does not occur then the corpus luteum involutes (luteolysis) this causes a fall in progesterone and estradiol removing the negative feedback on FSH and LH
-starting the cycle again
how many days is the menstrual and proliferative phase of the menstrual (endometrial) cycle?
days 1 to 14
how many days is the secretory (and premenstrual) phase of the menstrual (endometrial) cycle?
days 15 to 28
what occurs in the menstrual and proliferative phase of the menstrual (endometrial) cycle?
- endometrium breaks down and bleeds during menstruation
- estradiol stimulates endometrial growth from approx. days 6-14
- rapid tissue growth, including growth of glands and vasculature
what happens to the levels of progesterone during the menstrual and proliferative phase?
levels of progesterone decrease because of the corpus luteum breaking down
what occurs in the secretory phase of the menstrual (endometrial) cycle?
- after ovulation at day 14 the corpus luteum secretes progesterone and progesterone promotes endometrial maturation
- glands become secretory
- spiral arteries grow and coil
what becomes the dominant hormone in the secretory phase of the menstrual (endometrial) cycle?
progesterone
what happens if fertilisation and implantation does not occur in the secretory phase of the menstrual (endometrial) cycle?
- corpus luteum atrophies
- progesterone levels fall
- spiral arteries contract
- endometrial tissue breaks down and bleeding occurs
- shed tissue and blood removed via cervix and vagina (menstruation/menses)
fill in the blank:
ovarian/menstrual cycles occur between _____ and menopause
menarchy
fill in the blank:
a cohort of follicles begin to grow in response to signals from the _____ and pituitary - all but one of these follicles will undergo atresia
hypothalamus
fill in the blank:
secretion of large amounts of estradiol by the ____ follicle will cause the ____ ____ and subsequently ovulation and formation of the corpus luteum
dominant
LH surge
fill in the blank:
the endometrium undergoes cyclic periods of growth, maturation and breakdown in response to cyclic patterns in _____ and _____
estradiol
progesterone
