Menstrual Cycle Flashcards
What are signs and symptoms of abnormal uterine function?
Pain: dysmenorrhoea, chronic pelvic pain,
Bleeding: menorrhagia, amenorrhoea, oligomenorrhoea, intermenstrual bleeding, postcoital bleeding
Pregnancy: infertility, miscarriage, ectopic pregnancy
What are some disorders of the reproductive tract?
Polyps Fibroids Ovarian cysts Ectopic Hydrosalpinx
What are the roles of oestrogen?
Bone and muscle growth
Endometrial growth
Female secondary characteristics (breast/pubic hair)
What is the corpus luteum? What 3 hormones does it secrete?
After ovulation when the follicle breaks down - corpus luteum forms within the ovary
Oestrogen, Progesterone and Inhibin
What’s the role of FSH in the menstrual cycle?
In the follicular phase - maturation of a primary follicle and stimulation of oestrogen leading to ovulation
What’s the role of LH in the menstrual cycle?
Stimulates ovulation, corpus luteum development and progesterone secretion
What are the 3 phases of the menstrual cycle?
Menstrual phase 1-5 days
Proliferation phase 6-14 days
Secretory phase 15-28 days
What are the key things that happen during the menstrual phase?
When an ovum isn't fertilised Corpus luteum degenerates Progesterone and Oestrogen levels decline Layers of endometrium are shed = ready for new cycle
What stimulates a new menstrual cycle to occur?
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
What happens during the proliferation phase?
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
What’s the end of the proliferation phase?
Day 14 ovulation
What happens in the secretory phase?
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
What happens in the secretory phase if fertilisation doesn’t occur?
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
What’s the role of Inhibin and it what phase is it released?
Negative feedback to reduce FSH release and prevent follicle maturation during the luteal/secretory phase
What hormones stimulate ovulation?
Oestrogen and LH
What’s atresia?
Numerous follicles degenerate throughout the menstrual cycle as just one follicle (Graafian/dominant) one becomes ovulated
In menses, how much blood is lost and how long does it typically last?
35-80 mls
3-5 days
What are the 2 phases of the menstrual cycle, and the 3 phases of the uterine cycle?
Follicular and Luteal
Menses, Proliferative and Secretory
What are the two layers of the endometrium? Which layer is shed during menstruation?
Basalis and Functionalis
Functionalis layer is shed
At the end of the luteal phase, decline in which hormone causes the endometrium to shed and how?
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
During the proliferative phase, what 3 things does increasing oestrogen cause?
Increased vascularity (growth of spiral arteries into functional layer of endometrium)
Increased endometrial thickness
Development of increased numbers of secretory glands
Which phase is always fixed and 14 days long?
Secretory phase of the uterine cycle
What are the 4 main functional windows within the menstrual cycle?
Fertile
Implantation
Selection
Menstruation
When does the fertile window occur? How can you define it?
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%
What changes occur within the fertile window that make it most likely for pregnancy?
Cervical mucous becomes thinner and more alkaline
Propagated contractions in inner myometrium (junctional zone) to facilitate sperm transport
What and when is the implantation window?
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
What defines the selection window? What cell type is involved?
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
What’s decidualisation?
The transformation of endometrial storm all cells -> specialised secretory epithelial cells, which form nutritive matrix for trophoblast invasion and placenta formation
What causes a miscarriage?
Failure to decidualize properly (failure of trophoblast to implant properly)
What time of cells can be used after heart failure?
Endometrial stem cells (isolated from menstrual fluid)
What are some physical reproductive tract disorders?
Fibroids
Polyps
Cysts
All diagnosed by ultrasound
What are some disorders of the functional reproductive tract?
Defects in hormone production
Defects in hormone responsiveness (infection, scaring, stem cell deficiency, endocrine)
