Menstrual Cycle Flashcards
What are the names of the preparatory phase?
Follicular phase in ovaries
Proliferative phase in the uterus
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
Other terms for the waiting phase?
Luteal
Secretory
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)
Pre-ovulation
-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?
Copulation
Stress
