Physiology of menstrual cycle Flashcards
What causes the growth of a follicle in the menstrual cycle
FSH
What hormone has a burstlike release at the time of ovulation
LH
What hormones are released by the coprus luteum
Progesterone and oestrogen (not LH, LH causes the production of the corpus luteum after ovulation)
What are the 3 phases of the ovarian cycle?
Follicular phase (days 1-10) = hormones signal 10-20 follicles to grow on ovaries, oestrogen matures on oocyte.
Ovulatory phase (days 11-14) = oocyte undergoes cell division, follicle walls thin and ruptures. Oocyte enter the abdominal cavity near fimbrae of fallopian tube.
Luteal phase (days 14-28) = oestrogen levels drop, egg travels through the fallopian tube towards the uterus.
What structure of the fallopian tube allows the uptake of an oocyte in ovulation
Fimbrae
How is an oocyte moved along the fallopian tubes in ovulation?
Via cilia and fallopian tube contraction
How long after ovulation will implantation occur?
6-7 days
What effect can oestrogens have on the ovaries?
Affect maturation of reproductive organs, menstruation and pregnancy
What effect can progesterone have on the ovaries?
Helps maintain the uterine lining (keeps in thin)
What is the menstrual cycle
Series of cyclic changes in the endometrium in response to changes in levels of ovarian hormones
What are the stages of the menstrual cycle?
Menstrual phase (days 1-5) = functional layer of endometrium becomes detached from the uterine wall resulting in bleeding
Proliferative stage (days 6-14) = follicular development, increasing oestrogen, endometrium begins to proliferate and thicken
Secretory phase (days 15-22) = Rising levels of progesterone; enlargement of glands which begin secreting mucus and glycogen in preparation for implantation of the fertilized ovum
Describe the menstrual phase of the menstrual cycle
Days 1-5
Functional layer of endometrium becomes detached from uterine wall, resulting in bleeding
Describe the proliferative phase of the menstrual cycle
Days 6-14
Follicular development, increasing oestrogen, endometrium begins to proliferate and thicken
Describe the secretory phase of the menstrual cycle
Days 15-22
Rising levels of progesterone; enlargement of glands which begin secreting mucus and glycogen in preparation for implantation of the fertilized ovum
What are the most common causes of ovulatory dysfunction?
PCOS
Hypothalamic amenorrhea
Hyperprolactinaemia
Premature ovarian failure
How can obesity in women effect fertility
Obese women are less fertile, have higher rates of miscarriage and require higher doses of ovulation inducing agents
What is clomiphene citrate
Stimulates endogenous FSH production;
first line of treatment for those with absent or irregular ovulation but who have normal basal levels of endogenous oestradiol.
Works by blocking oestrogen reeceptors in the hypothalamus and the anterior pituitary.
What are the factors that may lead to hypogonadotrophic hypogonadism?
Low BMI (<20)
High intensity exercise
High-fiber+low-fat diets
Excessive stress
How can dopamine agonists be used to treat anovulation caused by hyperprolactinaemia?
Dopamine agonists inhibit prolactin release therefore causing an increase in endogenous GnRH secretion which stimulates pituitary gland secretion of LHandFSH - inducing follicle development and ovulation.
How can age effect fertility?
Decrease in pregnancy rate, increased miscarriage rate.
Increased risk of aneuploidy due to non-disjunction
What is ovarian reserve?
Number and quality of follicles left in the ovary at a given time
An accurate measure of the quantitative OR would involved counting all of the follicles present in both ovaries
