The Menstrual Cycle Flashcards
What hormone is produced by the hypothalamus and stimulates the anterior pituitary to produce sex hormones?
Gonadotropin-releasing hormone (GnRH)
What type of hormones are FSH and LH
Glycoproteins
Where are FSH and LH secreted from?
Anterior pituitary
What hormones do the ovaries produce in response to FSH and LH?
Oestrogen and progesterone
What type of receptors do LH and FSH bind to?
G-protein coupled receptors
What is the common biochemical precursor of steroid hormones?
Cholesterol (from acetate)
Steroid hormones can pass straight through the cell membrane and bind to nuclear hormone receptor - True or False?
True
What does a primordial follicle consist of?
A primary oocyte surrounded by a single layer of granulosa cells
What does a primary follicle consist of?
Fully grown ovum surrounded by many layers of granulosa cells
Accelerated growth of 6-12 primary follicles each month is caused by what?
LH and FSH
A layer of theca cells forms on the inside or outside of granulosa cell layers?
Outside
Starts on day of menses and ends with ovulation.
Follicular Phase - characterised by presence of a follicle
What phase comes after the follicular phase?
Luteal phase
What receptors do Theca and Granulosa cells express in follicular phase?
Theca - LH receptors
Granulosa - FSH receptors
What do Theca cells secrete upon stimulation by LH?
Androgens
What enzyme converts androgens to oestrogen in granulosa cells?
androgen aromatase
In the follicular phase does oestrogen have a positive or negative effect on the hypothalamus?
Negative
What is the function of inhibin B and from what cell is it produced?
Produced by granulosa cells and it inhibits FSH adn LH release
What is the function of anti-mullerian hormone?
suppresses growth of neighbouring follicles so you get a dominant follicle
What causes the oestrogen surge?
Androgens have a metabolic effect and cause proliferation of granulosa cells so more granulosa cells = more oestrogen being produced.
What is the effect of the oestrogen surge on granulosa cells?
They express LH receptors
What causes the surge in LH?
Increased oestrogen level causes a switch from negative feedback to positive feedback on pituitary gland
LH binding to receptors on granulosa cells causes the production of what?
Progesterone
What two processes is the LH surge necessary for?
Ovulation and oocyte maturation (from primary to secondary oocyte)
What is a polar body?
A byproduct of meiosis produced as a result of unequal cell division of oocyte. It contains chromosomes that chromosomes that are not needed
What stage of meiosis does the oocyte arrest at in second meiosis?
Metaphase
What two cell types is the corpus luteum made up of?
Granulosa cells and lutein cells that arised from theca interna cells.
What products does the corpus luteum secrete?
Oestrogen and progesterone and inhibin A which inhibits secretion of FSH
How many days does a corpus luteum tend to last if no fertilisation occurs?
12 days - final involution around 26th day of menstrual cycle
What feedback does the corpus luteum have on the anterior pituitary?
Negative - to inhibit FSH and LH
What are the three phases the uterus endometrium undergoes during a normal menstrual cycle and during what days do they normally occur on?
1) Menstruation (days 0-5)
2) Proliferative Phase (days 6-14)
3) Secretory Phase (days 15-28)
What is another name given to a mature follicle?
Graafian follicle
What causes menopause?
A lack of oestrogen being produced: when female stops producing oocytes she stops producing granulosa cells and hence oestrogen
What effect does Oestrogen have on the heart and liver?
regulates production of cholesterol (decreases build-up of plaque in the coronary arteries)
What effect does oestrogen have on the brain?
Helps maintain body temperature and protects against memory loss
What is hirsutism?
unwanted male patterning of facial hair - sometimes a symptom of menopause
Which of the following long-term problems of menopause could HRT make worse?:
1) Osteoporosis
2) dry vagina
3) Altzheimer’s disease
4) Ischaemic heart disease
3 and 4
In HRT why are progestogens usually prescribed as well?
Because if oestrogens are unapposed they stimulate endometrial hyperplasia and carcinoma
What females would you not need to give progestogens to along side HRT?
Those who have had a hysterectomy as they are not in danger of endometrial hyperplasia and carcinoma
Name 5 benefits of HRT
1) Relief of menopausal symptoms
2) osteoporosis prevention
3) reduce risk of colon cancer
4) general wellbeing
5) cardiac disease (in younger women)
Name 5 risks of HRT
1) Thrombosis (stroke)
2) Uterine cancer (oestrogen only)
3) Breast cancer
4) Cardiac disease (older women)
5) Alzheimer’s disease
How long do you have to have not had a period for to start on combined oestrogen replacement?
At least 1 year
What age is premature menopause defined to occur at or before?
<40yrs - 1% of women
Name some causes of premature menopause
1) Familial
2) surgical removal of ovaries
3) radiotherapy to the pelvis
4) chemotherapy
5) chromosomal abnormalities
6) Autoimmune disease
