FEMALE REPRODUCTIVE SYSTEM FUNCTIONS

Question 1

two functions of the ovary

Answer 1

production of gametes and sex hormones

Question 2

oocyte definition

Answer 2

a gametocyte, or germ cell, involved in reproduction

an immature egg cell

Question 3

explain limited number of oocytes

Answer 3

ovaries become populated with oogonia during fetal life

continue to divide by mitosis until a few weeks before birth

after this time, no new oocytes are produced, and thus each woman is born with a limited number

Question 4

around how many oocytes remain at puberty + how many are we born with?

Answer 4

born with 400,000

200,000 remain

Question 5

where do the oocytes mature?

Answer 5

fluid filled follicles

Question 6

follicle definition

Answer 6

cellular aggregation found in the ovaries that secretes hormones that influence stages in the menstrual cycle

each contain a single oocyte, immature ovum

Question 7

explain changes to oogonia during gestation

Answer 7

oogonia multiply and divide mitotically until the second/third trimester

the oogonia then enter meiosis I (formally named primary oocytes)

after beginning meiosis, the primary oocytes can no longer replicate

Question 8

what happens to the primary oocytes next?

Answer 8

primary oocytes are arrested at prophase 1 for years until puberty

Question 9

oogenesis definition

Answer 9

the production/ development of an ovum

Question 10

what causes meiotic prophase arrest?

Answer 10

due to lack of sufficient cell cycle proteins

Question 11

how is arrest maintained?

Answer 11

follicle and cAMP

Question 12

what occurs during the arrested phase?

Answer 12

build up stores of RNA and protein and then rest until puberty

Question 13

When does oogenesis begin again?

Answer 13

puberty

Question 14

explain continuation of oogenesis

Answer 14

immature ova resumes the cell divisions of meiosis 1 and produces two daughter cells

each cell receives an equal number of chromosomes

Question 15

what is not divided equally? + consequences

Answer 15

cytoplasm is not divided equally

cell with the cytoplasm forms the secondary oocyte

the other cell is termed the first polar body which is non functional so degenerates

Question 16

next stage of oogenesis

Answer 16

immediately after meiosis I , meiosis II begins however is arrested in metaphase II

the secondary oocyte is released from the ovary during ovulation

Question 17

what induces the completion of meiosis II?

Answer 17

fertilisation by sperm

Question 18

what is formed during meiosis II?

Answer 18

one polar body and one mature ovum

Question 19

how many mature ova are produced from one primary follicle?

Answer 19

1

Question 20

how many polar bodies?

Answer 20

2

Question 21

what happens to the polar bodies?

Answer 21

they generate

Question 22

process occurring at the same time as oogenesis

Answer 22

folliculogenesis

Question 23

folliculogenesis defintition

Answer 23

maturation of the ovarian follicle from a primordial follicle to large pre-ovulatory follicles

Question 24

main function of follicles

Answer 24

oocyte support

Question 25

what does folliculogenesis end in?

Answer 25

apoptosis or ovulation

Question 26

is folliculogenesis continuous or discontinuous? explain

Answer 26

continuous, meaning that at any time the ovary contains follicles in many stages of development

Question 27

stages of folliculogenesis

Answer 27

1. primordial follicle becomes activated, forming primary follicles. 2. primary follicles develop receptors to FSH 3. primary follicle to secondary follicle containing a fully grown oocyte 4. antrum forms adjacent to the oocyte, forming an antrum follicle - stimulated by LH and FSH 5. early tertiary- basic structure of mature follicle formed, no new cells detectable 6. preovulatory follicle formed

Question 28

term to denote follicle apoptosis

Answer 28

atresia

Question 29

what causes atresia?

Answer 29

developed follicles secrete oestrogen high levels of oestrogen decrease FSH (which normally inhibits follicular atresia)

Question 30

what does atresia result in?

Answer 30

selection of the dominant follicle

Question 31

explain follicle rescue

Answer 31

increase FSH shows to rescue follicles from atresia

Question 32

two important cell types in follicles

Answer 32

theca and granulosa cells

Question 33

granulosa cell function

Answer 33

form blood-ovary barrier convert androgens to estradiol and inhibins using aromatase after ovulation, they become granulosa lutein cells and produce progesterone

Question 34

theca cell function

Answer 34

synthesise androgens provide signal transduction between granulosa cells and oocytes

Question 35

stages of hormonal control of these cells

Answer 35

1. GRH released from hypothalamus to anterior pituitary via hypothalamo-pituitary axis 2. GRH results in release of FSH and LH from adenohypothysis 3. FSH stimulates granulosa cells to produce aromatase LH stimulates theca interna cells to stimulate androgen production

Question 36

ovum definition

Answer 36

the female gamete

Question 37

mature ovum outer layers

Answer 37

zona pellucida and corona radiata

Question 38

zona pellucida structure + function explained

Answer 38

thick membrane which persists for some time after fertilisation glycoprotein rich layer that is secreted by the oocyte contains sperm receptors protects the oocyte

Question 39

corona radiata structure + function explained

Answer 39

innermost layer of the cells of the culmulus oophorus, adjacent to the zona pellucida formed by enlarged granulosa cells

Question 40

menstrual cycle definition

Answer 40

regular changes that occur in the female reproductive system cycle is required for the production of oocytes and the preparation of the uterus for pregnancy

Question 41

two cycles in the menstrual cycle + definitions

Answer 41

ovarian cycle- changes that occur in the follicles of the ovary uterine cycle - changes in the endometrial lining of the uterus

Question 42

three phases of the ovarian cycle

Answer 42

follicular phase, ovulation and the luteal phase

Question 43

explain follicular stage

Answer 43

FSH secreted from the adenohypophysis in the last few stages of the menstrual cycle FSH induces proliferation of the granulosa cells and activation of aromatase which begins the secretion of oestrogen oestrogen stimulates hypothalamus to secrete GnRH, increasing LH which induces androgen synthesis high levels of oestrogen however inhibit FSH release from hypothalamus- leading to selection of dominant follicle

Question 44

explain ovulation stage

Answer 44

estradiol suppresses LH from the anterior pituitary when the egg is close to maturation, oestrogen reaches a peak which stimulates LH - known as the LH surge release of LH matures the egg and weakens the wall of the follicle in the ovary, causing the release of the secondary oocyte

Question 45

explain luteal phase

Answer 45

FSH and LH cause the remaining parts of the dominant follicle to transform into the corpus luteum which produces progesterone increase in progesterone induces the production of oestrogen progesterone also suppresses FSH and LH, which in turn stop the development of the corpus luteum corpus luteum degenerates, drop in progesterone triggers menstruation

Question 46

what prevents the atresia of the corpus luteum?

Answer 46

fertilisation of the egg syncytiotrophoblast produces hCG which is similar to LH and presevres corpus luteum

Question 47

when does luteolysis take place?

Answer 47

when not enough LH or FSH are being produced from hypothalamus, due to negative feedback from progesterone

Question 48

oestrogen function

Answer 48

promote secondary sexual characteristics, regulate the menstrual cycle

Question 49

three stages of uterine cycle

Answer 49

menstruation, proliferative and secretory

Question 50

explain menstruation

Answer 50

discharge of blood and mucosal tissues from the inner lining of the uterus through the vagina no fertilisation, no hCG leading to luteolysis which leads to a drop of progesterone which in turn results in menstruation

Question 51

explain proliferative phase

Answer 51

ovarian follicles mature, producing oestrogen oestrogen initiates the formation of a new layer of endometrium and vaginal crypts that produce mucus

Question 52

explain secretory phase

Answer 52

corresponds to the luteal phase progesterone produced by corpus luteum makes the endometrium receptive to the implantation of the blastocyst increase blood flow and uterine secretions and reduce smooth muscle contractiliy

Question 53

puberty definition

Answer 53

process of physical changes through which a child's body matures into an adult body capable of sexual reproduction

Question 54

onset of puberty

Answer 54

high GnRH pulsing, leading to a rise in LH and FSH

Question 55

what may cause GnRH pulsing?

Answer 55

leptin