Menstrual Cycle Flashcards
The whole menstrual cycle is made up of which 2 cycles?
Ovarian
Uterine
Approximately when is ovulation?
Day 14
Half way though cycle
In simple terms, what are the roles of the ovarian and uterine cycles?
Ovarian = preparation of gametes Uterine = preparation of endometrium
Why do we need a waiting phase?
To maintain the endometrium until a signal has been received to indicate whether or not fertilisation has occurred
Would need the endometrium to support the conceptus
When is the follicle capable of oestrogen secretion?
After a small amount of development due to FSH
Must have a theca interna
What happens in the mid-follicular phase?
A dominant follicle is recruited
Follicular oestrogen high - positive feedback effect starts
LH rises
Follicular inhibin rising - selective inhibition of FSH
When does progesterone production begin?
When granulosa cells become responsive to LH
When is meiosis I complete?
At ovulation
What are the effects of LH?
Ovulation
After ovulation the follicle is luteinised to secrete oestrogen and progesterone in large quantities
What is the luteal phase?
In ovarian cycle after ovulation
Corpus luteum lives for exactly 14 days unless hCG signal
Produces progesterone and oestrogen
Produces inhibin
Regresses spontaneously in absence of LH/hCG
What part of the embryo produces hCG?
Syncytiotrophoblast
Why is hCG not detected before 2 weeks after fertilisation?
Have to wait for syncytiotrophoblast to develop
This occurs in week 2 (the week of 2s)
What happens to the corpus luteum in pregnancy?
Supported by placental hCG
Produces steroid hormones to support the pregnancy
What are the 2 phases of the ovarian cycle?
Follicular phase (0-14) Luteal phase (14-28)
Briefly describe the follicular phase
Recruiting follicles and nominating a dominant
Briefly describe the luteal phase
Corpus luteum producing oestrogen and progesterone to keep things going until we know the status of fertilisation
What are the phases of the uterine cycle?
Menses (0-4 days) Proliferative phase (4-14 days) Secretory phase (14-28 days)
Simply, what happens in the secretory phase?
Endometrium becomes very glandular
How does menses occur?
Gonadal hormone decrease causes spasm in arteries
Causes ischaemia of endometrium leading to shedding of that tissue
What are the actions of oestrogen in the follicular phase?
Fallopian tube function Thickening of endometrium Growth and motility of myometrium Thin, alkaline cervical mucus Vaginal changes Changes in skin, hair and metabolism
What are the actions of progesterone in luteal phase?
Further thickening of endometrium Thickening of myometrium but reduction of motility Thick, acidic cervical mucus Changes in mammary tissue Increased body temp Metabolic and electrolyte changes
Why do we decreased motility of myometrium in the luteal phase?
Don’t want to expel the conceptus
Why does the cervical mucus become thick and acidic in the luteal phase?
Limits potential for infection
A normal cycle is between …
21 - 35 days
