Menstruation

menstrual cycle

1. The events in the menstrual cycle are :

2. stage 1 - Follicle stage
The anterior pituitary produces FSH which is
carried to the ovary where it stimulates
development of one or more graafian follicle

3. Stage 2 - Ovulation
Increased estrogen from
the follicle
1.Stimulates the pituitary
gland to produce LH and
inhibits FSH
2.Repair and thickening of
endometrium

4. Stage 3 – Corpus Luteum
LH surge occurs on day
12 triggering ovulation
The ruptured follicle
heals inside the ovary
forming the corpus
luteum
Yellow body
The corpus luteum
produces progesterone
Reduced amount of
oestrogen produced

5. Negative feedback –
Progesterone and oestrogen inhibits FSH and
LH and stimulates growth and blood supply of
endometrium.

6. Stage 4 - Menstruation
If an embryo is not present approximately 2
weeks after ovulation the corpus luteum
decomposes
Estrogen and progesterone levels decrease
FSH is not inhibited and is secreted by
pituitary.
Endometrium breaks resulting in
menstruation

7. If pregnancy occurs….
Corpus luteum released
Progesterone & oestrogen levels are high
Womb lining is intact
FSH production is inhibited

8. Menstrual cycle