2.2

Question 1

Describe the duration of the menstrual cycle. Why is their variation?

Answer 1

21-35 days

Variation in length of follicular phase.

Question 2

What are the three phases of the menstrual ccle

Answer 2

Follicular
Preovuatory
Luteal

Question 3

Describe the follicular phase. How long?

Answer 3

Preparation of the gamete (ovarian cycle).
Preparation of the endometrium (uterine cycle).
Stimulate development of a follicle in the ovary.
Uterus prepared for sped transport and implantation.
12-14 days long.

Question 4

Describe the pre-ovulatory phase

Answer 4

LH surge stimulates ovulation
Brief period of fertility (36 hours)
Formation of corpus luteum

Question 5

Describe the luteal phase.

How long?

Answer 5

LH maintains the corpus luteum in th eovary
Waiting to see if there is a pregnancy.
14 days.

Question 6

Give the changes occurring in the repro tract in the follicular phase due to rising oestrogen.

Answer 6

Fallopian tube
- Stimulates secretion and muscular contraction and growth of motile cilia.

Myometrium:
- Stimualtes growth and motility

Endometrium

• Increased thickness
• Secretes watery fluid conductive to sperm

Stimulates secretion of cervical mucus

Vaginal epithlium proliferates

Mildly anabolic

Question 7

Give the effects of progesterone on oestrogen primed cells in the luteal phase.

Answer 7

Fallopian tube:
Reduced motility, secretion and cilia activity.

Myometrium:
Further thickening
Redcued motility

Endometrium:
Stimulates further thickening
Increased secretion
Spiral arteries develop

Cervical mucus
Thickening and acidification
Inhibits sperm transport

Mildly catabolic

Raised body temp

Question 8

What happens following the sudden fall in progesterone and oestrogen in the luteal phase.

Answer 8

Secretory epithelium of endometrium collapse.
Apoptotic cell death
Dead tissue sheds as menstrual bleed
Spiral arteries contract to reduce bleeding.

Question 9

Give the hormonal changes in the early follicular phase.

Answer 9

Relatively high FSH/LH
Low but rising oestrogen
Very low progesterone

Question 10

Give the hormonal changes in the late follicular phase.

Answer 10

FSH falls
LH rises
Oestrogen levels rise dramatically.

Question 11

Give the hormonal changes during ovulation.

Answer 11

Rise in oestrogen is followed by LH surge.

Question 12

Give the hormonal changes in the early luteal phase.

Answer 12

FSH and LH low

Rising oestrogen and progesterone.

Question 13

Give the hormonal changes in the late luteal phase.

Answer 13

FSH and LH low

Oestrogen and progesterone are high with progesterone higher.

Question 14

Give the hormonal changes at the end of the luteal phase.

Answer 14

Progesterone then oestrogen falls.

Menstruation begins.

Question 15

Draw a graph of the endometrial and hormonal changes through the menstrual cycle.

Answer 15

-

Question 16

When is the menstrual cycle deemed to begin?

Answer 16

First day of menstrual bleeding, through this is physiologically the end of the previous cycle.

Question 17

What are the hormone levels at the beginning of the cycle?

Answer 17

Oe, Pro, In low
GnRH secretion is released from inhibition.
LH and FSH rise.
FSH more so as released from selective inhibition by inhibin.

Question 18

What are the actions of gonaotrophins in the follicular phase?

Answer 18

FSH binds to granulosa cells
Follicular development continues.
Theca intern appears.
Follicle now capable of oestrogen secretion.
Oestrogen and inhbin secretion rises.
FSH secretion is selectively inhibited by inhibit.
Rising oestrogen leads to GnRH stimulation and hence LH secretion.
LH continues to stimulate follicular development.

Question 19

What happens 12-14 days into the cycle?

Answer 19

Oestrogen and ihibin rise rapidly.
Oestrogen production no longer dependent on FSH.
Positive feedback of oestrogen stimulates LH surge.
This produces ovulation.

Question 20

Describe ovulation

Answer 20

Oestrogen falls dramatically.
Corpus luteum forms
Pogesterone production begins
Granulosa cells become unresponsive to LH
Meiosis I completes and Meiosis II starts.
Mature oocyte extruded.

Question 21

What happens after ovulation?

Answer 21

LH promotes oestrogen and progesteron secretion from the corpus luteum in large quantities.
Inhibin is still produced.
LH is now suppressed because of negative feedback and presence of progesterone.
As corpus luteum grows, more steroids are produced.
Rising oestrogen does not cause LH/GnRH surge due to rising progesterone.
Waiting phase.

Question 22

What happens if there is no pregnancy after the luteal phase? How long after luteal phase?

Answer 22

14 days
Corpus luteum regresses spontaneously.
P and O levels fall
Triggers menstrual bleed.
Relieves inhibition of GnRH, FSH and LH, triggering development of new follicles.

Question 23

What happens after the luteal phase if there is a pregnancy?

Answer 23

hCG released by placenta prevents corpus luteum regression:
Continues to secrete O and P
Supports early weeks of pregnancy. (After 12, placenta takes over)
Maintains the suppression of ovarian cycle.

Question 24

How long does it take from ovulation to menses?

Answer 24

14 days

Question 25

How does prolactin suppress fertility?

Answer 25

Suppresses FSH and GnRH

Question 26

In males, what happens if testosterone level rise?

Answer 26

GnRH is inhibited
Reduced LH and FSH
LH and FSH further reduced by testosterone reducing sensitivity of gonadotrophs to GnRH
Testosterone levels fall back.

Question 27

What happens of spermatogenesis proceeds to rapidly

Answer 27

Inhibin levels rise

Reducing secretion of FSH.