What is the term given to describe the inception of menstruation around puberty?
What triggers the menarche?
Increasing GnRH levels
What comprises an ovarian follicle?
An oocyte surrounded by granulosa and theca cells
What is the function of theca cells?
What is the function of granulosa cells?
Conversion of androgens (using aromatase) to oestrogens
What are the two key phases of the menstrual cycle?
- Follicular phase
- Luteal phase
Which days does the follicular phase typically occupy within the menstrual cycle?
Days 1 - 12
The follicular phase begins with __________
The follicular phase begins with menstruation
Which hormone begins to rise first in the follicular phase and what is its impact?
Gonadotrophin releasing hormone (GnRH)
Increases secretion of FSH and LH from the anterior pituitary
Which hormone acts on theca cells and what is the outcome?
Which hormone cats on granulosa cells and what is the outcome?
___________ levels rise throughout the follicular phase
Oestrogen levels rise throughout the follicular phase
____ causes maturation of follicles until a _________ (dominant) follicle emerges
FSH causes maturation of follicles until a Graafian (dominant) follicle emerges
Between which days does a surge in LH occur and what does it cause?
High levels of oestrogen have what impact on which hormone?
Inhibition of FSH
What happens to the remaining follicle after ovulation?
It becomes the corpus luteum and secretes progesterone (and some oestrogens)
What effect does progesterone have?
- Increases thickness and secretory activity of endometrium
- Increases basal body temperature
- Increases cervical mucus thickness
- Aids glandular development in the breasts
What effect do high progesterone levels have on which two other hormones?
Inhibition of FSH and LH
What happens when there is failure of fertilisation?
- Degeneration of the corpus luteum
- Fall in progesterone levels
- Fall in oestrogen levels
- Vasospasm of of arterioles supplying endometrium
- Necrosis of endometrium and menstruation
A fall in progesterone levels has which effect on which two other hormones?
Rise in FSH and LH
(inhibitory effect removed)
What is the most potent oestrogen produced and what does it cause?
- Secondary sexual charcateristics
- Contributes to bone and CV health
Which hormone stimulates the transformation of the empty follicle to the corpus luteum?