Menstrual cycle

Question 1

What are the 2 phases of the menstrual cycle?

Answer 1

The follicular phase and the luteal phase.

Question 2

When in the menstrual cycle does the follicular phase occur?

Answer 2

The follicular phase is from the start of menstruation to the moment of ovulation (the first 14 days in a 28-day cycle).

Question 3

When in the menstrual cycle does the Luteal phase occur?

Answer 3

The luteal phase is from the moment of ovulation to the start of menstruation (the final 14 days of the cycle).

Question 4

What are oocytes?

Answer 4

a finite number of cells that have the potential to develop into eggs

Question 5

What are granulosa cells?

Answer 5

Granulosa cells surround the oocytes, forming structures called follicles.

Question 6

What are the 4 stages of follicle development in the ovaries?

Answer 6

1. Primordial follicles
2. Primary follicles
3. Secondary follicles
4. Antral follicles (also known as Graafian follicles)

Question 7

Follicle

Answer 7

Oocytes surrounded by granulosa cells

Question 8

At what stage of follicle development is FSH required?

Answer 8

Secondary follicle stage

The process of primordial follicles maturing into primary and secondary follicles is always occurring, independent of the menstrual cycle.
Further development after the secondary follicle stage requires stimulation from FSH.

Question 9

What is the role of the granulosa cells in the secondary follicle development stage?

Answer 9

At the start of the menstrual cycle, FSH stimulates further development of the secondary follicles.

As the follicles grow, the granulosa cells that surround them secrete increasing amounts of oestradiol (oestrogen).

Question 10

What does rising estrogen levels (secreted from Granulosa cells) in the secondary follicle stage do to the cervical mucus?

Answer 10

The rising oestrogen causes the cervical mucus to become more permeable, allowing sperm to penetrate the cervix around the time of ovulation.

Question 11

Granulosa cells secrete estrogen starting from the secondary follicle stage; what do rising estrogen levels do to the hypothalmic-pituitary axis?

Answer 11

The oestradiol has a negative feedback effect on the pituitary gland, reducing the quantity of LH and FSH produced.

Question 12

What does the LH spike just before ovulation cause?

Answer 12

One of the follicles will develop further than the others and become the dominant follicle.

Luteinising hormone (LH) spikes just before ovulation, causing the dominant follicle to release the ovum (an unfertilised egg) from the ovary.

Question 13

When is ovulation?

Answer 13

Ovulation happens 14 days before the end of the menstrual cycle, for example, day 14 of a 28-day cycle, or day 16 of a 30-day cycle.

Question 14

What is ovulation?

Answer 14

The release of an egg from your ovary, into your fallopian tube.

Question 15

What is the corpus luteum?

Answer 15

After ovulation, the follicle that released the ovum collapses and becomes the corpus luteum.

Question 16

Corpus luteum role

Answer 16

The corpus luteum secretes high levels of progesterone, which maintains the endometrial lining.

This progesterone causes the cervical mucus to become thick and no longer penetrable. The corpus luteum also secretes a small amount of oestrogen.

Question 17

Role of progesterone in the luteal phase

Answer 17

Causes the cervical mucus to become thick and no longer penetrable.

Question 18

What happens to the corpus luteum when fertilization occurs?

Answer 18

When fertilisation occurs, the syncytiotrophoblast of the embryo secretes HCG. HCG maintains the corpus luteum. Without hCG, the corpus luteum degenerates.

Question 19

What maintains the corpus luteum during fertilisation?

Answer 19

The syncytiotrophoblast of the embryo secretes HCG. HCG maintains the corpus luteum.

Question 20

What happens to the corpus luteum if fertilisation does not occur during the luteal phase of the menstrual cycle?

Answer 20

Corpus luteum degenerates

(When fertilisation occurs, the syncytiotrophoblast of the embryo secretes HCG. HCG maintains the corpus luteum. Without hCG, the corpus luteum degenerates)

Question 21

During fertilisation, HCG maintains the corpus luteum. However if fertilisation does not occur the corpus luteum degenerates; what happens at this stage?

Answer 21

The corpus luteum degenerates and stops producing oestrogen and progesterone.

This fall in oestrogen and progesterone causes the endometrium to break down and menstruation to occur. Additionally, the stromal cells of the endometrium release prostaglandins. Prostaglandins encourage the endometrium to break down and the uterus to contract.

Question 22

Role of prostaglandins in the menstrual cycle

Answer 22

Prostaglandins encourage the endometrium to break down and the uterus to contract.

Question 23

What is menstruation?

Answer 23

Involves the superficial and middle layers of the endometrium separating from the basal layer.

The tissue is broken down inside the uterus and released via the cervix and vagina.