E4. The female reproductive system Flashcards
function of female reproductive tracts?
-production of ova (oogenesis)
-reception of sperm
-transport of the sperm and ovum to common site for union (fertilisation of conception)
-maintenance of the developing fetus until it can survive in the outside world
-giving birth (parturition)
-nourishing the infant after birth (lactation)
what are the primary female reproductive organs?
-ovaries
-uterus (womb)
-oviducts (fallopian tubes)
-vagina
-vulva (Labii major and minor)
-clitoris
-mammary glands
-pelvis
ONE NOTE
What does the ovary contain?
-Primary follicles (germ cells and granulosa cells)
-Graafian follicles (germ cells, granulosa and theca cells)
Function of the oviduct (fallopian tube)?
-collects released ova and serves as the site of fertilisation
-transports fertilised egg to uterus
function of the uterus?
-thick-walled hollow comprising of the endometrium and myometrium
-responsible for maintaining the fetus during pregnancy
what is the cervix and cervical canal?
lower section of the uterus with exit into the vagina
what is the vagina?
-a muscular tube connecting uterus to external environment
-repository for sperm during intercourse
Describe the ovary
-made up of the outer cortex and central medulla
-contains follicles
-contains corpus lutea
-contains at birth all sex cells they will ever have (10^5 to 10^6)
ONE NOTE
function of corpus lutea?
A corpus luteum is a mass of cells that forms in an ovary. It is a temporary organ that appears every menstrual cycle and disappears if fertilisation does not occur. It produces hormones that prepare the uterus for pregnancy.
ONE NOTE
Describe the fallopian tubes
-functional links between ovaries and uterus
-site of fertilisation
-ciliated glandular, epithelial lining
ONE NOTE
Describe the cervix
-Narrow sphincter of smooth muscle tissue
-Holds developing fetus inside uterus
-Forms a mucus plug
ONE NOTE
Describe oogenesis
ONE NOTE
Primary follicles develop into?
larger (secondary) follicles containing oocyte, granulosa cells and theca cells
what three things can happen to primary follicles?
1) Die- atresis
2) Remain arrested in the pre-antral phase (13-50 years)
3) Grow into a Graafian/Mature/Antral Follicle
-Basis of selection is unknown but occurs once a month but is thought to involve FSH
ONE NOTE
Describe the graafin follicle phase
-Conversion of Secondary Follicles to Graafian Follicles associated with proliferation of granulosa and theca cells and development of a fluid-filled space called the antrum
-This process is under the control of three hormones which shows evidence of synergistic interaction
ONE NOTE
How does the graafian follicle phase work?
1) LH stimulates 20,22 desmolase activity in theca cells and testosterone production.
2) FSH stimulates the granulosa cells of the follicles.
i) aromatase activity which in turn produces oestradiol from testosterone.
ii) LH receptors in preparation for LH ‘surge’.
FSH causes an increase in LH receptors on theca cells.
3)Oestradiol (Estradiol) causes proliferation of granulosa cells.
compare oogenesis and spermatogenesis
i) Not all primordial germ cells undergo full oogenesis.
ii) Fixed number of oocytes at birth which diminishes during life
(only 400 successfully released).
iii) First meiotic division of oocyte occurs after release from the ovary. Second meiotic division is triggered upon entry of sperm
iv) Hormones level vary throughout the month
Describe ovulation
-Graafian Follicle migrates to surface of ovary and ruptures to release secondary oocyte into Fallopian tube under the influence of LH
-Primary oocyte undergo first meiotic division to secondary oocyte and polar body just before ovulation.
-Residual element of follicle forms Corpus Luteum (an endocrine unit) which provides balance of gonadal steroids necessary for implantation of fertilized ovum
ONE NOTE
What steroid and peptide hormones are involved in female reproduction?
-steroid hormones: oestrogen and progesterone
-peptide hormones: follicle stimulating hormone (FSH) and luteinising hormone (LH) (both gonadotrophins), human chorionic gonadotrophin (hGC), oxytocin, prolactin
Describe female puberty
-Hypothlamus produces GnRH
-Pituitary produces LH and FSH
-Ovaries produce Oestrogen and Progesterone
-Menstrual cycle starts
-Secondary female sex characteristics
What two jobs does a female have?
1) produce a haploid gamete- changes in ovary during 1st half of menstrual cycle involving oestrogen
2)support the fetus- changes in uterus during second half of menstrual cycle involving progesterone
Describe day one of menstruation
one note
Describe menstrual cycle
Ovarian cycle lasts 24-32 days and involves changes in hormones, the ovary and womb.
ONE NOTE
Describe the follicular/proliferative phase - pre-ovulatory?
-Follicles release oestrogens under basal pulsatile release (90 min) of FSH and LH. Anterior pituitary hormones release determined by pulsatile GnRH release.
i) Initially oestrogen production increases due to synergy between low levels of FSH and LH, which in turn causes -ve feedback on further FSH and LH pituitary release. But……
200pg/ml oestradiol for > 2 days causes reversal of feedback control and LH ‘surge’
ii) ‘LH surge’ stimulates LH receptors on granulosa cells of follicle.
