The Menstrual Cycle Flashcards
What are the aims of the menstrual cycle?
Single oocyte selection Creation of haploid cells Regular, spontaneous ovulation Cyclical changes in the vagina, cervix and Fallopian tubes Uterus preparation Support of the fertilised egg
How long is a typical menstrual cycle?
28 days
When is the first day of the menstrual cycle?
First day of bleeding
What happens at (roughly) day 14 of the menstrual cycle?
Ovulation
What is the name of the first phase of the menstrual cycle?
Follicular phase
What is the name of the second phase of the menstrual cycle?
Luteal phase
What happens in the follicular phase of the menstrual cycle?
Growth of antral follicles up to ovulation
What is the follicular phase dominated by?
Oestradiol production from the follicles
What is the luteal phase dominated by?
Progesterone production from the corpus luteum
What happens in the luteal phase of the menstrual cycle?
Formation of the corpus luteum from the empty follicle
What are the feedback mechanisms that happen in the follicular phase?
Decrease in negative feedback, negative feedback reinstated, switch from negative to positive feedback and then negative feedback again
What induces the first decrease in negative feedback in the follicular phase?
Decrease in progesterone from the corpus luteum
What causes the reinstation of negative feedback in the follicular phase?
Oestradiol levels increase
What causes the switch from negative to positive feedback in the follicular phase?
As the dominant follicle grows it releases large amounts of oestradiol
What happens to the follicles when the FSH levels begin to rise at the start of the follicular phase?
Follicles are recruited into the menstrual cycle and produce oestrogen