Week 5 - Hormones and Reproduction - The Female Flashcards
Describe the anatomy of the female reproductive tract + the role for each part
Uterus - found in the middle of the lower pelvis
Ovary - have 2 connected to each side of the uterus
What are the female reproductive hormones
Oestrogen - granulosa cells
Progesterone
Inihibin - secreted from granulosa cells
Androgen - secreted from theca cells
- androgen secreted then acts on granulosa cells
Describe the key events of the menstural cycle
Inc. ovarian cycle, uterine cycle
Ovarian Cycle:
1. Follicular Phase
- have oocytes (egg) in ovary which are stimulated = growth + differentiation = primary folicules
- primary folicules have follicular cells (surrounding oocyte) grow into secondary follicules, development of granulosa + theca cells
- granulosa cells are surrounded by theca cells
- granulosa cells secrete inhibin + oestrogen
- thecae cells secrete androgen
- granulosa cells secrete material (that forms a shell around oocyte / egg), this material recruits ovarian stromal cells
- dominant follicle selected (by FSH) completes maturation (tertiary follicule) + is released at ovulation
- Ovulation
- folicule ruptures leaving behind corpus luteum (endocrine gland)
- occurs on day 14 (in a 28 day cycle) - Luteal Phase
- corpus luteum secretes oestogen + progeseterone (prepares body for potential pregnancy)
- if NO FERTILISATION = c.luteum degenerates after 10 days ~ degeneration stimulates menstruation
- if fertilisation occurs egg becomes embryo + secretes hCG (hormone) which maintains c.luteum
- occurs from day 14 to end of cycle
Uterine Cycle:
- Shedding of the uterine lining (due to ↓ in oestrogen and progesterone) = MENSTRUATION
- ↓ in sex steroid = prostaglandin release
- prostaglandin causes vasoconstriction in endometrium tissue = shedding due to breakdown in tissue
- PROLIFERATION: oestrogen stimulates endometrial glands + blood vessel growth
- SECRETORY PHASE: pogesterone secreted prevents over proliferation (counteracts oestrogene)
- continued gorwth, secretion of fluids on prep. for potential embryo implantation
How does endometriosis occur (menstruation disorder)
Endometriosis - is the establishment + growth of endometrial tissue outside the uterus (ectopic growth)
How does it arise:
- During reflux menstruation endometrial tissue fragments shed + as they pass through fallopian tubes become established in ectopic sites
- these ectopic fragments continue to cycle under hormonal control (proliferation)
Risk factor: family history
Ectopic- growth where it’s not supposed to be
How does the Hypothalamic-Pituitary-Ovarian (HPO) Axis work
- Hypothalamus (in brain)
- secretes GnRH in pulsatile manner
- GnRH acts on pituitary gland stimulating release of gondatropins - Anterior Pituitary Gland
- Gondatropins (FSH + LH) are released and act on the ovaries - Ovary
- FSH & LH - stimulates sex steroid production (oestrogen + prgesterone)
- FSH acts on granulosa cells
- LH acts on theca cells
- FSH - stimulates folicle development
-
Explain how the HPO axis: negative feedback works
Androgen secreted from theca cells (androgen acts on granulosa cells)
Oestogen + inhibin secreted from granulosa cells
All above feedsback to HPO axis:
- hypothalamus to ↓ GnRH secretion
- anterior pituitary gland to ↓ FSH and LH
Negative feedback occurs during early / mid follicular phase
Explain how the HPO axis: positive feedback works
Positive feedback occurs during late follicular phase (before ovulation)
- ↑ in oestrogem (from granulosa cells) stimulates further production of FSH and LH
- ↑ in FSH and LH tiggers ovulation
Compare regulation of the HPG axis (men) and HPO axis (women)
MAIN DIFFERENCE:
- Male gondatropins control sex steroid prodcution (testosterone, inhibin etc.) THEN sex steroids control sperm production
- Females gondatropins control both sex steroid production + folicle maturation
- Men ONLY have neagtive feedback
- Women have negative and positive
- negative during early / mid follicular phase
- positive during late follicular phase (before ovulation)
How does female contraception work
MAJORITY work by INHIBITING the HPO Axis
- if ↑ levels of sex steroid (oestrogen / progesterone) = ↓ active HPO Axis
- high levels of oestrogen specifically will inhibit the axis
- negative feedback as the contraception causes ↑ steroid levels which feedsback to hypothalamus + pituitary gland to stop secreting hormones
INHIBITED HPO Axis causes:
- ↓ GnRH, FSH and LH released = further release of sex steroids is inhibited
- inihibts ovulation = follicular development is inhibited = NO pregnancy
-
Assisted Reproductive Technology (ART)
ART may be used for:
- female infertility
- endocrine disorders
- reduced oocyte quality (occurs as we age)
AIM: to take oocyte from woman and sperm from man, create embryo in lab which is put into woman
In ART need to suppress the HPO
- suppress HPO by using GnRH agonist and antagonist
- to prevent ovary from releasing its own eggs
Long term exposure to GnRH Agonists causes:
- loss of response to GnRH (by pituitary gland)
- GnRH receptor downregulation
- inhibition of FSH / LH SECRETION
This allows control of HPO Axis for times egg collection for IVF
AIM: many follicles developed then oocytes are collected
What are the consequences of oestrogen loss (menopause)
- Vasomotor symptoms
- hot flushes, night sweats - Genitalia
- pain during sex - Bladder
- increased UTIs - Depression
Long-term:
- Wound healing impaired
- Cognitive function impaired
- Bone density decrease (with age, over 60)
- Weaker immune system (oestrogen is anti-inflammatory)
Treatment for the loss is HRT:
(HRT - hormone replacement therapy)
- low dose of oestrogen to improve symptoms
- usually 10mg daily
