Reproductive System 3- Female

Question 1

What is the female reproductive system made up of?

Answer 1

1) Gonads: Ovaries- Produces eggs + hormones
2) Reproductive tract: Fallopian tubes

Also have: Oviducts, uterus, vagina, vulva

Question 2

What are some features of the menstrual cycle?

Answer 2

Characterised by complex cycling

Menstrual cycle begins at puberty and persists until menopause

Outward sign: Periodic vaginal bleeding

Internal cyclical changes in ovaries, uterus, cervix/ vagina, hormones and breasts/behaviour

Question 3

What are the 2 female sex hormones? What effects do they have?

Answer 3

1) Oestrogen:
Ova maturation= helps ova to get ready to be ovulated
Female secondary sexual characteristics= Breast development
Effects on endometrium ; myometrium
Feedback on pituitary gondadotrophins

2) Progesterone
Effects on endometrium and myometrium
Feedback on pituitary gonadotrophins
Thermogenic= Makes temperature rise

Endometrium: Inner layer of uterus
Myometrium: Thick middle layer of smooth muscle in uterus

Question 4

What is oogenesis?

Answer 4

Production of eggs
Undifferentiated primordial germ cells formed in fetal ovary
Happens during last part of fetal life: Begins first meiotic division= Primary oocytes
Remain in meiotic arrest until puberty
At the start of each menstrual cycle a few oocytes begin to develop but usually only 1 is ovulated per cycle

1) Germ cells in ovaries undergo mitotic division
2) Germ cells then undergo meiotic division= Primary oocyte
3) At birth, each ovary contains about half a million primary oocytes. Meiosis does not occur until puberty
4) Puberty= Divides into 2 cells, a large egg and tiny first polar body and egg (secondary oocyte) is selected for ovulation, releasing the mature egg until after the second meiotic division

1 oocyte: 1 ovum

Question 5

What are the phases of the ovarian cycle?

Answer 5

The ovarian cycle refers to the series of changes in the ovary during which the follicle matures, the ovum is shed and the corpus luteum develops.

1) Follicular phase: (First half of cycle)
Period of follicular growth in the ovary
So basically egg grows
Day 6: One dominant remains and some ateretic follicles
Only a few follicles survive and reach final stages of growth= Dominant follicle develops to point where it releases its egg

2) Ovulation: Once one or more follicles have ripened, the ovary releases the oocyte(s) during ovulation

3) Luteal phase: After ovulation, transformation of a raptured follicle into corpus luteum= Secretes hormones (oestrogen and progesterone) that continue the preparations for pregnancy= Prepares endometrium
If pregnancy does not occur: Corpus luteum creases to function after about 2 weeks and ovarian cycle begins again

Question 6

What is the uterine cycle and what are the different stages?

Answer 6

Describes the changes to the endometrial lining of the uterus

Menstruation:
1)FSH released by pituitary= Causes follicles to begin to mature, compete for dominance in ovaries
Endometrium lining breaks down

Proliferative phase:

2) Follicle secretes oestrogen= High levels= Endometrium wall builds up in anticipation of pregnancy= More blood supply
3) Oestrogen initially inhibits the release of FSH= negative feedback
4) Oestrogen has positive feedback with oestrogen= More is released from follicle

5) Ovulation: Oestrogen switches so that it starts to stimulate release of FSH and LH by pituitary gland 
High levels (sudden surge) of LH= causes fully developed follicle to burst, release the ovum into the oviduct 

Secretory Phase:

6) LH also stimulates the follicle to develop into corpus leuteum= Secretes progesterone
7) Progesterone stimulates the uterus to complete development of endometrium wall= Ready to receive embryo
8) Progesterone also inhibits the release of LH and FSH= stops release of oestrogen
9) Corpus lutem degenerates over the next 10 days, less progesterone is secreted
10) Levels of progesterone gets low enough so that menstruation is triggered= FSH starts to increase again= Cycle starts again

Question 7

What is the mechanism of dominance for developing follicles?

Answer 7

Oestrogen secretion of dominant follicle= Increased to a level that directly lowers the levels of LH and FSH= Leads to deaths of most of the recruited follicles

Dominant follicle continues to mature

Question 8

What are the specialised features of an egg?

Answer 8

1) Has stored nutrients and factors needed for early embryo development
2) Egg coat= Blocks polyspermy
3) Able to attract sperm by chemotaxis= Chemical given off