Female reproductive system LO3, LO4

Question 1

Vagina

Answer 1

The vagina provides a passageway to:
– eliminate menstrual fluids
– receive the penis during intercourse
– expel fetus during child birth
- It is a thin-walled tube
- Both muscular and elastic: stretch and recoil
- Acidic environment helps keep the vagina free of
infection but makes it hostile to sperm

Question 2

Uterus

Answer 2

Hollow, thick muscular organ that:
– receives, retains and nourishes offspring
- Consists of the body (major region), fundus (top region)
and cervix (joins to the vagina)
- Glands in the mucosa of the cervix secrete mucous that block spread of bacteria into uterus from vagina

Question 3

uterine wall

Answer 3

Perimetrium: outermost layer
Myometrium: bulky, middle muscular layer
- contracts to expel baby
Endometrium: inner, mucosal layer
- allows for implantation of the fertilised egg
- made up of 2 layers:
– Functional layer (stratum
functionalis): undergoes cyclic changes due to ovarian hormones and is shed during menstruation
–Basal layer (stratum basalis): Unresponsive to ovarian hormones, regenerates functional layer following menstruation

Question 4

Uterine tubes / fallopian tubes

Answer 4

• Receive ovulated oocytes
• Typical site where fertilisation normally takes place
• Ciliated finger-like projections (fimbriae) sweep over the ovary draw the oocyte into the tube
• Muscular movements and beating cilia carry the oocyte towards the uterus

Question 5

ovaries

Answer 5

2 small, almond-shaped organs that:
– produce female gametes (oocytes)
– secrete female sex hormones (oestrogen and progesterone)
Each ovary consists of the:
– medulla: inside region which is highly vascularised
– cortex: outside region where follicles are matured to release oocyte

Question 6

Oogenesis

Answer 6

Occurs in the ovaries
– Begins in the fetal period – by birth, a female has a
lifetime supply of primary oocytes (~2 million in total)
- oocytes stay in a suspended state at least until puberty (at least 10-14 years)
– 250,000 primary oocytes remain at puberty
– A small number of primary oocytes are recruited
each month – but only one is selected to go through
meiosis to form the mature ovum (secondary oocyte)

Question 7

The ovarian cycle – two phases

Answer 7

– Follicular phase (d 1-14): follicle growth, ovulation occurs at the end of this stage
– Luteal phase (d 15-28): period of corpus luteum activity

Question 8

Follicular phase

Answer 8

1-2. Primordial follicle to primary follicle
3. primiary follicle to secondary follicle
4. Secondary follicle to late secondary follicle
5. late secondary follicle to vesicular follicle
6. ovulation

Question 9

Ovulation

Answer 9

• The bulging follicle eventually ruptures the wall of the ovary and the oocyte is released
• The fluid helps to flush the oocyte out of the follicle
• Oocyte is surrounded by granulosa cells
• A number of follicles are being prepared within the
  ovary at any one time
• Increases in LH (and FSH) trigger ovulation

Question 10

Luteal phase

Answer 10

7. Corpus Luteum is formed
8. (a) Corpus Luteum degenerates
9. (b) Corpus Luteum can persist cycle starts again

Question 11

Hormonal regulation follicular phase

Answer 11

1.GnRH released by the hypothalamus stimulates the anterior pituitary gland to release FSH and LH
2.FSH stimulates follicle maturation
3.FSH stimulates the thecal cells and granulosa cells to secrete oestrogens
4.Increasing levels of oestrogens stimulate a surge in LH secretion which triggers ovulation

Question 12

Hormonal regulation of luteal phase

Answer 12

1.The LH surge transforms the ruptured follicle into the corpus luteum (CL)
2.The CL produces oestrogen, progesterone and inhibin
3. If fertilisation does not occur the CL degenerates, hormone levels decline and the cycle begins again

Question 13

uterine (menstrual) cycle

Answer 13

Cyclic changes of the functional zone of the
endometrium occur in response to ovarian hormones
– Endometrial changes are coordinated with the ovarian cycle
- ovarian cycle is driven by hormones released by anterior pituitary
- the uterine cycle is driven by oestrogen and progesterone released by the ovary

Question 14

uterine (menstrual) cycle days

Answer 14

Day 1-5: Menstrual phase (menses)
– shedding of the functional layer of the endometrium
- oestrogen and progesterone are low
Day 6-14: Proliferative (pre-ovulatory) phase
– rebuilding of the functional layer of the endometrium
– cervical mucous becomes less sticky to allow entry of sperm
- this phase is stimulated and sustained by ovarian oestrogens
– ovulation occurs at the end of this phase
Day 15-28: Secretory (post-ovulatory) phase
– begins immediately after ovulation
– endometrium prepares for implantation
- stimulated by progesterone and oestrogens from corpus luteum
- if fertilisation does not occur, the CL degenerates –> low progesterone –> breakdown of the rndometrium –> menses begins again