1.3 Menstrual cycle

Question 1

What is the average length of the menstrual cycle?

Answer 1

28 days (21-35)

Question 2

What do we call the first period of a girl’s life?

Answer 2

Menarche

Question 3

What are the three phases of the ovarian cycle and how long is each?

Answer 3

Follicular phase - first 14ish days from start of menstruation to ovulation

Ovulation (14 days before bleeding)

Luteal phase - latter 14 days (ovulation to start of menstruation)

Question 4

What is a follicle made of?

Answer 4

oocytes surrounded by granulosa cells make a follicle

Question 5

What stages of development does a follicle go through?

Answer 5

• primordial follicle
• primary follicle
• secondary follicle
• antral follicle (aka Graafian)

primordial develop into primary and then secondary independent of menstrual cycle. Secondary have FSH receptors that must be stimulated for them to develop and compete to become the dominant follicle.

Question 6

What happens in the ovaries during the first 14 days of the menstrual cycle (the follicular phase)?

Answer 6

Rising FSH causes development of several primordial follicles into in the end a single, selected tertiary follicle which will then expel the ovum so that it can escape the ovaries during ovulation. The structure left behind is called the corpus luteum.

Question 7

What does the developing secondary follicle / dominant follicle release?

Effects?

Answer 7

oestradiol which:

• which has negative feedback on pituitary FSH and LH
• suddenly has poistive feedback and causes LH surge and ovulation
• cervical mucous to be permeable and also build up endometrium

Question 8

What happens in the ovaries during the latter 14 days of the menstrual cycle (the luteal phase)?

Answer 8

The corpus luteum (the structure left behind by the ovum) release progesterone and a little bit of oestrogen before being slowly broken down into first the corpus albicans before being fully degraded.

(progesterone maintains lining and makes cervical mucous thick)

Needs HCG from fertilised embryo to survive.

Question 9

What are the three phases of the uterine cycle and how long is each?

Answer 9

Menses - first 7 days

Proliferative stage - days 7-14

Secretory phase - Latter 14 days

Question 10

What is happening to the uterus during menses of the menstrual cycle?

Answer 10

There is a breakdown of the uterus endometrium.

Question 11

What is happening to the uterus during the proliferative phase of the menstrual cycle?

Answer 11

The endometrium is built up/thickened to be ready for implantation.

Question 12

What is happening to the uterus during the secretory phase of the menstrual cycle?

Answer 12

The endometrium is maintained whilst the corpus luteum is continuously secreting hormones, before both structures begin to break down and eventually menses starts.

Question 13

What are the two pituitary hormones involved in the menstrual cycle?

Answer 13

Follicular stimulating hormone (FSH) Luteinizing hormone (LH)

Question 14

What are the two ovarian hormones involved in the menstrual cycle?

Answer 14

Oestrogen Progesterone

Question 15

What is the hormone that is at its highest during the first week of the menstrual cycle and is responsible for initiating the follicular phase of the ovarian menstrual cycle?

Answer 15

Follicular stimulating hormone (FSH)

Question 16

What is the hormone that has a small rise around day 3 or 4 of the menstrual cycle which initiates the release of another hormone during this phase?

Answer 16

Oestrogen which initiates the release of luteinizing hormone (LH)

Question 17

What is the hormone largely responsible for the release of the oocyte in ovulation by having a sudden rise in concentration on about day 13?

Answer 17

Luteinizing hormone (LH)

Question 18

What is the hormone responsible for the proliferative stage of the uterine cycle?

Answer 18

Oestrogen

Question 19

What is the hormone produced by the corpus luteum?

Answer 19

Progesterone (if fertilised the embryos syncytiotrophoblast releases HCG which maintains the corpus luteum and therefore progesterone) and a little bit of oestrogen.

Progesterone will maintain endometrial lining and make cervical mucous thick.

Question 20

What are the hormones responsible for the maintenance of the endometrium in the secretory phase of the uterine cycle?

Answer 20

Progesterone and oestrogen

Question 21

What causes the breakdown of the endometrium and hence the beginning of the menses and the cycle?

Answer 21

The degradation of the corpus luteum means that levels of progesterone decrease bit by bit and eventually the endometrium can no longer be maintained.

Question 22

What stimulates the release of FSH to start the follicular phase of the ovarian cycle?

Answer 22

Low levels of progesterone and oestrogen.

Question 23

How is the endometrium maintained in pregnancy?

Answer 23

The implanted embryo will produce human chorionic gonadotrophin which acts to maintain the corpus luteum in the same way as LH and FSH.

Question 24

What happens to the endometrium when oestrogen and progesterone fall?

Answer 24

Fall in oestrogen and progesteron causes the endometrium to break down.

Also stromal cells in the endometrium release prostaglandins which encourage breakdown and uterine contraction.

Question 25

What is the average age of menarche in the UK?

Answer 25

12.9 years

Question 26

How short and long can the menstrual cycle be without being considered abnormal?

Answer 26

21-45 in young women 21-31 in older adults

Question 27

What are the symptoms that have been reported during menses and the preceding two weeks?

Answer 27

Pain

Acne

Tender breasts

Bloating

Feeling tired

Question 28

What are the symptoms of premenstrual syndrome (PMS)?

Answer 28

Stress

Anxiety

Insomnia

Headache

Fatigue

Increased mood swings

Emotional sensitivity

Changes in libido

Question 29

How do we treat premenstrual syndrome (PMS)?

Answer 29

Normally COCP unless contraception is an undesired effect