Menstrual Cycle Flashcards
What two cycles does the menstrual cycle consist of?
Ovarian cycle: release of ova
Uterine cycle: build up/break down of uterine lining
What are the three phases of the menstrual cycle?
Menstrual phase: 1-5 days, loss of uterine endometrium and blood loss
Proliferative: 6-14 days, regrowing the uterine endometrium lining, development of ovarian follicle, ovulation on ~ day 14
Luteal phase: 14-28 days maturation of endometrium and development of corpus luteum
Describe the hormonal control of the menstrual cycle?
The hypothalamus produces Gonadotrophin Releasing Hormone > this stimulates the anterior pituitary gland to produce Follicle Stimulating Hormone and Leutenising Hormone
FSH: Development of the follicle, production of oestrogen
LH: Some development of the follicle, ovulation, secretion of oestrogen and progesterone from corpus luteum
How do the ovarian and anterior pituitary hormones control the menstrual cycle via positive and negative feedback?
FSH increase at the start of the cycle causes the follicles to begin to mature.
This causes an increase in oestrogen
The most developed follicle produces further oestrogen (positive feedback) which inhibits FSH to make the developed Graafian follicle the only mature follicle (negative feedback)
The high oestrogen causes a surge in LH which causes ovulation
After ovulation the follicle becomes a corpus luteum, producing oestrogen and progesterone
These inhibit LH & FSH (negative feedback)
Progesterone builds up and develops the endometrium lining
Menses occurs when the corpus luteum degenerates and progesterone and oestrogen stops being produced by it, FSH is produced again, and the cycle starts over.
What effect does oestrogen have on the body in the proflierative phase?
Cervical mucus increases and becomes wetter to facilitate the passage of sperm
Relaxed the cervix, increased vascularity, open os
Can cause sodium retention which causes water retention and bloating
What is the effect of progesterone on other areas of the body at its peak in the cycle
Post-ovulation; cervical mucus becomes thicker, cervix becomes harder and os becomes tighter
Rise in body temperature
Increased pigmentation
Low serotonin, increased carb cravings
