Session 4 - The Menstrual Cycle

Question 1

Where is gonadotrophin releasing hormone (GnRH) produced?

Answer 1

Hypothalamus

Question 2

What is the action of GnRH?

Answer 2

Acts on the anterior pituitary to release gonadotrophins - FSH and LH

Question 3

What are the actions of gonadotrophins on the ovary?

Answer 3

Promote follicular development

Promote production of ovarian hormones (steroid hormones, inhibin)

Question 4

Why is pulsatile GnRH release an absolute requirement for fertility?

Answer 4

If GnRH receptors are exposed to the continuous presence of GnRH for too long they become desensitised.
FSH and LH production stops.
Gonadal steroid production stops.

Question 5

Why is endometriosis treated with a GnRH agonist?

Answer 5

Endometriosis is the presence of ectopic endometrium. It will grow in response to gonadotrophins. By treating with a GnRh agonist, the ovaries will be continuously exposed to GnRH, meaning the GnRh receptors will become desensitised and stop responding to it, therefore stoping the production of LH and FSH. This means the endometriosis will stop growing and the symptoms will be relieved.

Question 6

What are the two phases of the ovarian cycle?

Answer 6

Follicular phase

Luteal phase

Question 7

What are the three phases of the menstrual cycle?

Answer 7

Menses
Proliferation phase
Secretory phase