Menstrual Cycle

Question 1

What are signs and symptoms of abnormal uterine function?

Answer 1

Pain: dysmenorrhoea, chronic pelvic pain,
Bleeding: menorrhagia, amenorrhoea, oligomenorrhoea, intermenstrual bleeding, postcoital bleeding
Pregnancy: infertility, miscarriage, ectopic pregnancy

Question 2

What are some disorders of the reproductive tract?

Answer 2

Polyps
Fibroids
Ovarian cysts
Ectopic
Hydrosalpinx

Question 3

What are the roles of oestrogen?

Answer 3

Bone and muscle growth
Endometrial growth
Female secondary characteristics (breast/pubic hair)

Question 4

What is the corpus luteum? What 3 hormones does it secrete?

Answer 4

After ovulation when the follicle breaks down - corpus luteum forms within the ovary
Oestrogen, Progesterone and Inhibin

Question 5

What’s the role of FSH in the menstrual cycle?

Answer 5

In the follicular phase - maturation of a primary follicle and stimulation of oestrogen leading to ovulation

Question 6

What’s the role of LH in the menstrual cycle?

Answer 6

Stimulates ovulation, corpus luteum development and progesterone secretion

Question 7

What are the 3 phases of the menstrual cycle?

Answer 7

Menstrual phase 1-5 days
Proliferation phase 6-14 days
Secretory phase 15-28 days

Question 8

What are the key things that happen during the menstrual phase?

Answer 8

When an ovum isn't fertilised
Corpus luteum degenerates
Progesterone and Oestrogen levels decline
Layers of endometrium are shed
= ready for new cycle

Question 9

What stimulates a new menstrual cycle to occur?

Answer 9

The drop in progesterone and oestrogen during the menstrual phase cause an increase in GnRH release from the hypothalamus = release of FSH and LH increase at beginning of new cycle

Question 10

What happens during the proliferation phase?

Answer 10

Ovarian follicle is stimulated by FSH to mature
Primary follicle -> dominant follicle -> mature follicle which is then ovulated
Ovarian follicle matures and produces oestrogen
Stimulates endometrium to thicken in preparation for Graafian follicle

Question 11

What’s the end of the proliferation phase?

Answer 11

Day 14 ovulation

Question 12

What happens in the secretory phase?

Answer 12

Corpus luteum produces rising levels of progesterone
Endometrium becomes oedematous and secretory glands produce watery mucous to help passage of spermatozoa through the uterus to the uterine tubes

Question 13

What happens in the secretory phase if fertilisation doesn’t occur?

Answer 13

Corpus luteum breaks down due to the decline in LH
Lack of hormones causes blood vessels suppling the endometrium to go into spasm
Cells die and menstruation begins on day 28

Question 14

What’s the role of Inhibin and it what phase is it released?

Answer 14

Negative feedback to reduce FSH release and prevent follicle maturation during the luteal/secretory phase

Question 15

What hormones stimulate ovulation?

Answer 15

Oestrogen and LH

Question 16

What’s atresia?

Answer 16

Numerous follicles degenerate throughout the menstrual cycle as just one follicle (Graafian/dominant) one becomes ovulated

Question 17

In menses, how much blood is lost and how long does it typically last?

Answer 17

35-80 mls

3-5 days

Question 18

What are the 2 phases of the menstrual cycle, and the 3 phases of the uterine cycle?

Answer 18

Follicular and Luteal

Menses, Proliferative and Secretory

Question 19

What are the two layers of the endometrium? Which layer is shed during menstruation?

Answer 19

Basalis and Functionalis

Functionalis layer is shed

Question 20

At the end of the luteal phase, decline in which hormone causes the endometrium to shed and how?

Answer 20

If no implantation in the luteal phase, then corpus luteum degenerates so progesterone levels decline

Decrease in Progesterone = spiral arteries in functional endometrium contract = loss of blood supply = endometrium becomes ischaemic and necrotic

Functional endometrium is therefore shed

Question 21

During the proliferative phase, what 3 things does increasing oestrogen cause?

Answer 21

Increased vascularity (growth of spiral arteries into functional layer of endometrium)

Increased endometrial thickness

Development of increased numbers of secretory glands

Question 22

Which phase is always fixed and 14 days long?

Answer 22

Secretory phase of the uterine cycle

Question 23

What are the 4 main functional windows within the menstrual cycle?

Answer 23

Fertile
Implantation
Selection
Menstruation

Question 24

When does the fertile window occur? How can you define it?

Answer 24

4-5 days before ovulation and 1 day after (eg if ovulation is on day 14, then fertile window = days 10-15)

= days in the cycle when probability of intercourse resulting in a pregnancy is greater than 5%

Question 25

What changes occur within the fertile window that make it most likely for pregnancy?

Answer 25

Cervical mucous becomes thinner and more alkaline

Propagated contractions in inner myometrium (junctional zone) to facilitate sperm transport

Question 26

What and when is the implantation window?

Answer 26

5 days after ovulation and lasts 2-4 days

Synchronises embryo development with developmental status of the endometrium as endometrium expresses molecules necessary for attachment and invasion of blastocyst

Question 27

What defines the selection window? What cell type is involved?

Answer 27

After implantation window (21-23 days) and lasts until onset of menstruation

Decidual cells = have ability to sense quality of implanting embryo to either rapidly dispose or support placenta development

Question 28

What’s decidualisation?

Answer 28

The transformation of endometrial storm all cells -> specialised secretory epithelial cells, which form nutritive matrix for trophoblast invasion and placenta formation

Question 29

What causes a miscarriage?

Answer 29

Failure to decidualize properly (failure of trophoblast to implant properly)

Question 30

What time of cells can be used after heart failure?

Answer 30

Endometrial stem cells (isolated from menstrual fluid)

Question 31

What are some physical reproductive tract disorders?

Answer 31

Fibroids
Polyps
Cysts

All diagnosed by ultrasound

Question 32

What are some disorders of the functional reproductive tract?

Answer 32

Defects in hormone production

Defects in hormone responsiveness (infection, scaring, stem cell deficiency, endocrine)