(P2)Menstrual Cycle

Question 1

How do high levels of oestrogen trigger menstruation?

Answer 1

They stimulate the release of more LH from the pituitary gland, which triggers ovulation, which causes the corpus luteum to release progesterone.
If there’s no fertilisation, oest and pro levels fall which trigger menstruation

Question 2

How do low levels of progesterone cause thickening of uterus lining?

Answer 2

It allows FSH to be released, which stimulates growth and maturation of eggs in the ovary, which stimulates the production of oestrogen, which thickens the wall