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Flashcards in Menstrual Cycle Deck (20):

What happens in the preparation phase?

Follicles grow in the ovary
Uterus prepares for sperm transport and implantation of the conceptus
Changes occur to facilitate sexual interactions


What are the names of the preparatory phase?

Follicular phase in ovaries
Proliferative phase in the uterus


Other terms for the waiting phase?



What happens in the waiting phase?

Corpus luteum is in the ovary
Changes occur in preparation for pregnancy
Ended by shedding of part of endometrium


What are the gonadal steroids and the gonadotrophins?

Steroids - oestrogen and progesterone
Trophins - LH and FSH


Actions of the gonadotrophins?

Follicular phase
-FSH binds to granulosa cells
-LH binds to thecal cells (theca interna)

-LH surge stimulates ovulation

Luteal phase
-LH maintains the corpus luteum


Which hormones does the corpus luteum secrete?

Progesterone and a bit of oestrogen


What is the actions of the gonadal steroids in the follicular phase?

Oestrogen stimulate Fallopian tube function
Thickening of endometrium (secretes fluid to support sperm)
Growth and motility of myometrium (muscle contraction - sperm transport)
Vaginal changes
Changes in skin, hair, metabolism, calcium metabolism


What is the effect of gonadal steroids in the luteal phase?

Progesterone acts on oestrogen primed cells to cause more thickening of endometrium into secretory form
Thickening of myometrium but reduced motility
Thick, acid cervical mucus
Changes in mammary tissue
Increased body temperature
Metabolic changes
Electrolyte changes


Why is thick, acid cervical mucus produced in the luteal phase?

Protects the uterus from sperm and bacteria - action of contraception


How does the brain monitor the growth of follicles?

The bigger the follicle, the more oestrogen it produces


Why is there high FSH at the start of the menstrual cycle?

Corpus luteum absent, follicles only partially developed
Therefore little secretion of steroids or inhibin so little inhibition at the hypothalamus or anterior pituitary


What does the FSH do at the start?

Binds to granulosa cells, causing follicular development to continue and the theca interna develops


What does the developing follicle start to secrete and what are the effects?

Granulosa cells secrete oestrogen stimulated by LH and inhibin
Inhibin inhibits FSH and no new follicles can develop
The oestrogen exerts positive feedback at the hypothalamus so LH levels rise but FSH cannot due to inhibin


What factors can affect when ovulation occurs?



What happens after ovulation?

Corpus luteum forms spontaneously
Begins to secrete oestrogen and progesterone which maintains suppression of FSH
LH is also suppressed because positive feedback is inhibited by progesterone


What happens in the luteal phase?

Corpus luteum grows and secretes more steroids
After exactly 14 days it dies


What does the death of the corpus luteum cause?

Rapid fall in steroids levels
Stimulates menses
Relieves inhibition of FSH a
Begin again


What is the interval between ovulation and menses?

Always 14 days


If conception occurs, what happens?

Conceptus implants
Developing placenta secretes human chorionic gonadotrophin which preserves the corpus luteum
Corpus luteum secretes increasing amounts of steroids
Many physiological changes and the placenta will soon secrete more
By 12-14 weeks, corpus luteum no longer supports pregnancy