Menstrual Cycle (Normal Physiology,Menopause and Pre-menstrual dysphoric syndrome)) Flashcards
Name the two phases in the menstrual cycle
Follicular phase
Luteal phase
Average length of menstrual cycle?
28 days.
What pituitary axis controls the menstrual cycle?
Hypothalamus-pituitary-gonadal axis
Describe how the female HPG axis works
- Hypothalamus secretes GnRH
- GnRH travels down anterior pituitary gland and bind to receptor on gland
- This promotes release of LH and FSH from the anterior pit
- LH and FSH travel in blood stream to the ovaries
- LH and FSH bind to the ovaries, stimulating production of oestrogen and inhibin.
- Increasing levels of oestrogen and inhibin have negative feedback effect on hypothalamus and anterior pit
- This leads to decreased production of GnRH, LH< FSH.
- This results in decreased production of oestrogen and inhibin.
Name hormones involved in menstrual cycle
GnRH, LH, FSH, Oestrogen, Progesterone, Inhibin, activin
Describe release of hormones in female HPO axis
Pulsatile manner
Why is HPO axis in females pulsatile?
- Persistent presence of GnRH would lead to desensitisation of its receptors on gonadotrophs (in ant pit gland).
- So FSH and LH production would cease
- Gonadal steriod production would cease
What type of feedback do oestrogen, progesterone and inhibin have on pituitary and hypothalamus?
NEGATIVE
Describe the early follicular phase (days 0-5 of the menstrual cycle)
No ovarian hormone production (i.e no oestrogen and inhibin made)
Granulosa cells (endocrine cells in ovary) secrete activin
* This incerases FSH production, and have increase FSH receptors on granulosa cells
* Reduced production of androgens by theca cells at this point (so less oestrogen is made).
Collectively, this increases FSH levels, so:
* to stimulate follicle growth
* theca interna appears
* enhanced aromatase function –> so the follicle is now capable of enhanced oestrogen production
The follicle with the most FSH = the dominant follicle - sometimes called Graafian follicle.
Dominant Follicle/Graafian follicle’s granulosa cells switch from producing activin to producing inhibin
Describe the late follicular phase (days 5-14 of the menstrual cycle)
Dominant follicle/Graafian follicle granulosa cells** produce oestrogen and inhibin **
Oestrogen:
* Increases FSH receptors on the follicle (so the dominant follicle continues to grow)
* Initially exert negative feedback to reduce FSH production
* Increases LH receptors on granulosa cells to prep for ovulation
Inhibin:
* **Reduces FSH **production
* Helps LH to increase theca cells androgen production (androgens are converted to oestrogen)
Oestrogen and inhibin continue to rise.
How is FSH important in the production of oestrogen?
FSH enhances the function of aromatase.
Aromatase converts androgen –> oestrogen
Describe what happens in the ovulatory phase (day 14)
Oestrogen rises (independent of FSH)
High levels of oestrogen exert positive feedback on the hypothalamus and anterior pituitary
Results in a surge in LH production
There is no rise in FSH, due to presence of inhibin
Granulosa cells start secreting **progesterone **
How do high levels of LH change the membrane of the Graafian follicle?
Membrane becomes thinner.
Follicle ruptures releasing oocyte
What happens after follicle rupture? (but before luteal phase begins)
Secondary oocyte matures into mature ovum
Mature ovum is released into peritoneal space
It is taken into the fallopian tube via the fimbriae.
Describe the luteal phase of the menstrual cycle
Starts once ovulation has occured.
LH and FSH now stimulate remaining Graffian follicle to develop into corpus luteum (i.e. follicle is luteinised)
Corpus luteum produces progesterone (also secretes oestrogen and inhibin but that’s not as important)
Oestrogen and progesterone exert **negative feedback on LH **
Levels of FSH and LH fall, so corpeus luteum dedgenerates.
Degeneration of corpus luteum results in loss of progesterone production.
Falling progesterine levels** trigger mensturation** - then we are back to start of early follicular phase!
In the luteal phase, progesterone levels increase. What does this result in?
- Endometrium becoming receptive to implantation of blastocyst
- negative feedback causing decreased LH and FSH
- increase in woman’s basal body temperature
Which hormones are needed to maintain corpeus luteum?
FSH and LH
(That’s why when they fall in the luteal phase, the C.L degenerates)
What happens if an ovum is fertilised?
ie. what hormones, what happens to corpeus luteum
Fertilised ovum produced hCG, which has similar function to LH
hCG prevents degeneration of corpus luteum = get continued production of progesterone
Continued production of progesterone = prevent menstruation
What takes over role of corpus luteum from ~8 weeks gestation
Placenta
What are the three phases of the uterine cycle?
Menstrual
Proliferative
Secretory
Name for inside lining of uterus?
Endometrium
What are two layers of endometrium?
Functional layer
basal layer
Describe the growth of the functional layer of the endometrium
Grows thicker in response to oestrogen
Is shed in menstruation
Describe the basal layer of the endometrium
Forms the foundation from which the functional layer develops
(is not shed!)
What happens during the proliferative phase of the uterine cycle?
a) think about the hormones involved
b) how do those hormones affect the endometrium
Endometrium is exposed to increases levels of oestrogen (as LH and FSH have stimulated its production)
Oestrogen stimulates repair and growth of the functional layer
This allows recovery from recent menstruation
What is endometrium made up of?
Epithelium + stroma
When does the secretory phase of the uterine cycle begin?
Once ovulation has occured
Describe what happens in he secretory phase
a) name hormone(s) involved
b) what happens as a result?
Driven by progesterone produced by the corpus luteum
Results in secretion of substances from endometrial glands - so uterus becomes ready for embryo implantation
Describe the menstrual phase of the uterine cycle (i.e how the period comes about)
At the end of the luteal phase the corpus luteum degenerates.
Loss of corpus luteum results in decreased progesterone production
Reduced progesterone levels cause the spiral arteries in he functional layer of the endometrium to contract
This causes a loss of blood supply to this layer, so the functional endometrium becomes ischaemic and necrotic.
As a result, the functional endometrium is shed and exits through the vagina as menstruation.
In what phase of the menstrual cycle is oestrogen highest?
Follicular phase
In what phase of the menstrual cycle is progesterone highest?
Luteal phase
What are the actions of oestrogen in a woman’s health?
Both in menstrual / uterine cycle and other effects on the body
- Thickens endometrium
- fallopian tube function (increases function of cilia of epithelial cells to waft oocyte along tube)
- growth and motility of myometrium (middle layer of uterus, endometrium is innermost, perimetrium is outermost)
- Thin alkaline cervical mucus
- Vaginal changes
- Changes in skin, hair and metabolism
What are actions of progesterone in a woman’s health?
Both in menstrual / uterine cycle and other effects on the body
- further thickening of the endometrium
- thickening of mymoetrium and reduction of motility
- Thick, acidic cervical mucus
- Development of breast tissue
- increased body temp
- metabolic changes
- electrolyte changes
What factors can cause disruption to the menstrual cycle?
Physiological - pregnancy, lactation
Emotional stress
Body weight
Infertility
What should be asked in a menstrual history? (not gynaecological history)
Duration of periods
* average 5 days
Frequency
* how often?
* are they regular?
* predictable
Menstrual blood flow
* Ask about volume
* are they heavier than usual?
* are you flooding sanitary towels
* are you passing blood clots larger than 10p coin?
* do heavy periods impact on day to day life?
* any abnormal bleeding patterns? intermenstrual, post-coital
Menstrual pain/ dysmenorrhoea
* Painful periods interfere w/ day to day life?
* more painful than usual?
Date of LMP
* if late, consider preg test
Age at menarche
* how old when they started periods
* early? increased risk od breast cancer and cardiovascular disease.
Menopause (if relevant)
* age of onset
* ask about perimenopausal sx - hot flushes, vaginal dryness
Define premenstrual syndrome
NICE cks:
a condition characterized by psychological, physical, and behavioural symptoms occurring in the luteal phase of the normal menstrual cycle (that is, the time between ovulation and onset of menstruation)
Define premesntrual dysphoric disorder
NICE cks:
A severe form of PMS occuring when a woman sufferes from at least 5 out of 11 distinct psychological premenstrual symptoms, one of which must include mood
The symptoms must strictly occur in the luteal phase of the menstrual cycyel and must be severe enough to disrut daily functioning
What psychological symptoms are experienced in PMS?
- mood swings
- irritability
- depressed mood
- anxiety
- feeling out of control
- poor concentration
- change in libido
- food cravings.
What physical symptoms are experienced in PMS?
- breast tenderness
- bloating
- headaches
- backache
- weight gain
- acne
- gastrointestinal disturbance