Menstrual Cycle and HPO Axis - week 24

Question 1

How does LH and FSH get released? (HPO Axis)

Answer 1

Hypothalamus released GnRH
Anterior pituitary released LH AND FSH

Question 2

Describe the ovarian cycle

Answer 2

Follicular phase (1-14)
One oocyte dominates in primary follicle of ovary
Granulosa cells proliferate
Theca cells proliferate
LH increased and oestrogen increases to mature follicle
Oestrogen now POS FEEDBACK on hypothalamus and pituitary
LH surge = ovulation

Luteal phase (15-28)

Drop LH and FSH
Corpus Luteum develops = progesterone increase
No fertilisation = breakdown of CL

Question 3

Describe the endometrial cycle

Answer 3

Menses (1-5)
Bleeding and breakdown of endometrial tissue

Proliferative phase (5-14)
Endometrial thickening from oestrogen
Thinning of mucous
Spiral arteries form

Secretory phase (14-28)
Progesterone = glycogen secretion
Mucous thickens to block canal and protect embryo
Artery spasms
Endometrial degeneration

Question 4

What is the feedback loop for the hormones during period?

Answer 4

Normally oestrogen has a neg feedback on FSH and LH

Approx day 13, oestrogen now pos feedback on hypothalamus and anterior pituitary and turns on GnRH, FSH and LH

Back to neg feedback after ovulation