Physiology of menstrual cycle

Question 1

What causes the growth of a follicle in the menstrual cycle

Answer 1

FSH

Question 2

What hormone has a burstlike release at the time of ovulation

Answer 2

LH

Question 3

What hormones are released by the coprus luteum

Answer 3

Progesterone and oestrogen (not LH, LH causes the production of the corpus luteum after ovulation)

Question 4

What are the 3 phases of the ovarian cycle?

Answer 4

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.

Question 5

What structure of the fallopian tube allows the uptake of an oocyte in ovulation

Answer 5

Fimbrae

Question 6

How is an oocyte moved along the fallopian tubes in ovulation?

Answer 6

Via cilia and fallopian tube contraction

Question 7

How long after ovulation will implantation occur?

Answer 7

6-7 days

Question 8

What effect can oestrogens have on the ovaries?

Answer 8

Affect maturation of reproductive organs, menstruation and pregnancy

Question 9

What effect can progesterone have on the ovaries?

Answer 9

Helps maintain the uterine lining (keeps in thin)

Question 10

What is the menstrual cycle

Answer 10

Series of cyclic changes in the endometrium in response to changes in levels of ovarian hormones

Question 11

What are the stages of the menstrual cycle?

Answer 11

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

Question 12

Describe the menstrual phase of the menstrual cycle

Answer 12

Days 1-5

Functional layer of endometrium becomes detached from uterine wall, resulting in bleeding

Question 13

Describe the proliferative phase of the menstrual cycle

Answer 13

Days 6-14

Follicular development, increasing oestrogen, endometrium begins to proliferate and thicken

Question 14

Describe the secretory phase of the menstrual cycle

Answer 14

Days 15-22
Rising levels of progesterone; enlargement of glands which begin secreting mucus and glycogen in preparation for implantation of the fertilized ovum

Question 15

What are the most common causes of ovulatory dysfunction?

Answer 15

PCOS
Hypothalamic amenorrhea
Hyperprolactinaemia
Premature ovarian failure

Question 16

How can obesity in women effect fertility

Answer 16

Obese women are less fertile, have higher rates of miscarriage and require higher doses of ovulation inducing agents

Question 17

What is clomiphene citrate

Answer 17

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.

Question 18

What are the factors that may lead to hypogonadotrophic hypogonadism?

Answer 18

Low BMI (<20)
High intensity exercise
High-fiber+low-fat diets
Excessive stress

Question 19

How can dopamine agonists be used to treat anovulation caused by hyperprolactinaemia?

Answer 19

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.

Question 20

How can age effect fertility?

Answer 20

Decrease in pregnancy rate, increased miscarriage rate.

Increased risk of aneuploidy due to non-disjunction

Question 21

What is ovarian reserve?

Answer 21

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