female reproductive system and pregnancy

Question 1

describe the anatomy and cell types found in the ovaries

Answer 1

they’re the female gonads where development of ova occurs
the cortex of the ovaries contains the oocytes in it’s outer germinal layer

the inner medulla has the blood and lymphatic vessels

granulosa cells secrete oestrogen (17B-oestradiol)
Theca cells secrete produce progesterone

Question 2

describe the anatomy of the fallopian tubes

Answer 2

10cm long, start of the oviduct is the infundibulum which has fimbriae which help capture the egg
there are lots of smooth muscle cells to aid in movement of the egg, with ciliated and secretory cells also being present

Question 3

describe the anatomy of the uterus

Answer 3

perimetrium (outer layer), myometrium and endometrium (changes with menstrual cycle)
has simple columnar epithelial cells
spiralling capillaries

Question 4

describe the anatomy of the cervix and the vagina

Answer 4

cervical canal connects uterus to vagina, with an interior and exterior os

vagina is the birth canal, 8-10cm long
has thin distensible wall of adventitia (secures the organ), muscularis mucosa (elastic fibres and smooth muscle cells)

made up of stratified squamous epithelia
rich in glycogen, which gets fermented by bacteria to produce lactic acid, lower pH, inhibit pathogens

Question 5

FSH and LH stimulate which hormones, which then do what?

Answer 5

progesterone from theca cells
oestrogen from granulosa
these develop the ovum, maintain the corpus luteum and maintain pregnancy

Question 6

what is the hypothalamic-pituitary-gonadal axis?

Answer 6

drives menstrual cycle
Hyp releases gonadotropin releasing hormone GnRH
Hyp is connected to anterior pituitary by the hypophyseal portal system

at the AP a GPCR is activated by GnRH and an IP3 cascade is activated, causing exocytosis of gonadotropins FSH and LH

Question 7

describe what happens in the stages of the ovarian cycle and how it links to the stages of the menstrual cycle

Answer 7

follicular phase: FSH and LH is high to increase follicle growth, these cells release oestrogen, which encourages endometrial growth, so the follicular phase of the ovarian cycle overlaps with the proliferative phase of the endometrial cycle. Oestrogen is providing -ve feedback on the hypothalamus now

mid-cycle/ovulation: Oestrogen concentration rises to critical level (blue peak), which instead causes positive on the hypothalamus causing a surge in LH, resulting in ovulation

Luteal phase: Egg released, follicle now = corpus luteum.
Corpus luteum secretes mostly progesterone (and some oestrogen) to promote endometrial gland formation, so lines up with the secretory phase of the endometrial cycle
Corpus luteum degenerates if there is no fertilisation - less progesterone and oestrogen are produced - the endometrial functional layer degenerates = menses phase of the endometrial cycle
luteal phase - progesterone provides -ve feedback to hyp. to reduce FSH and LH

Question 8

describe how oogenesis works

Answer 8

actually begins when a person is in the womb
primordial germ cells produce oogonia by mitosis
from there 2 million of 7 million enter prophase and become oocytes that remain suspended for years until ovulation (puberty) but by then there’s only 400,000, one egg released per month from alternating sides until menopause

Question 9

describe how folliculogenesis works

Answer 9

a few follicles enter development each month, the second meiotic division of ova only actually gets completed upon fertilisation, if fertilisation doesn’t occur, corpus luteum regresses to corpus albicans

Question 10

what happens in the phases of the menstrual cycle?

Answer 10

proliferative phase - cervix is secreting mucus that is watery and elastic, creating channels that propel sperm forward
oestrogen is dominant and supports the growth of the endometrium, glands stroma and those spiralling arteries

secretory phase - progesterone is dominant, glands increase mucus secretion so that it thickens and now acts as a barrier
growth slows, stroma cells are swollen (oedematous)
spiral arteries elongate and coil

menses - if there is no implantation the functional layer of the endometrium sheds (not the lower layer the zona basalis)

Question 11

what are three options of hormonal contraceptives?

Answer 11

progesterone only
monophasic or fixed combo
multiphasic (different doses of each hormone throughout the course)

Question 12

what are all hormonal contraceptives involved in function-wise, like how do they work?

Answer 12

feeding back to hypothalamus to downregulate GnRH - less FSH and LH - to prevent folliculogenesis and ovulation

progesterone also causes inhospitable mucus and reduces fallopian motility
it also reduces endometrial glycogen to reduce potential for growth

Question 13

why are placebos included in contraceptive pills?

Answer 13

to create a daily habit

Question 14

how does the morning after pill work?

Answer 14

you don’t know what phase of your cycle you are in so it’s important that the pill have multiple modes of action

1) alters endometrium - prevents lining from preparing to receive an egg so if fertilisation has occurred implantation shouldn’t

2) prevent release of an egg as sperm can hang around for days

3) thickens cervical fluid to prevent sperm reaching the uterus

Question 15

what specialisations are there to assist with fertilisation?

Answer 15

smooth muscle contraction, flagella of the sperm and mucus channels
cilia in the oviduct are critical in helping the egg get from the ovary across the tiny gap to the fimbriae, any issues with this can lead to ectopic pregnancy

Question 16

what cells surround the egg?

Answer 16

the egg is surrounded by a layer of granulosa/cumulus/corona radiate cells

Question 17

what is sperm capacitation and how does the sperm penetrate the egg?

Answer 17

sperm capacitation is how well a sperm can penetrate an egg

it uses it’s acrosome - an acidic vacuole on it’s head containing a hydrolytic enzyme
the zona pellucida surrounds the egg - a collection of glycoproteins ZP1, 2 and 3, the sperm’s receptors attach to ZP3 and hydrolyse the zona pellucida

Question 18

what happens upon fertilisation and how?

Answer 18

second meiotic division is triggered by an increase in intracellular calcium and other sperm are prevented form entering

Question 19

explain what happens to the egg (once released) pre implantation

Answer 19

when the egg is fertilised in the oviduct it is called the conceptus
for 3 days it moved along the oviduct dividing
smooth muscle cell then stops it’s progression to allow for more preparation of the uterus
at the 3 day mark there’s 12-ish cells and we call it a morella, it’s just entering the uterine cavity
then it develops into a blastocyst with a fluid filled gap in the middle, implanting at 6 days

Question 20

describe the structure of a blastocyst

Answer 20

blastocele is the fluid filled gap in the middle, where there is an inner cell mass
the trophectoderm surrounds this
the zona pellucida surrounds that

Question 21

for implantation: what is the hormone ratio like?
the blastocyst promotes what process?
how does it decrease chances of rejection?

Answer 21

low oestrogen : progesterone, so it’s the secretory phase

promotes decidualisation (the decidua contains the glands, immune cells, blood + lymph vessels, stromal cells and glycogen) to provide nourishment

decreases inflammation by silencing chemokine genes

Question 22

describe the four stages of endometrium invasion

Answer 22

Hatching = zona pellucida disintegrates

Apposition = orientates itself so that the inner cell mass is towards the endometrial epithelium

Adhesion = integrin and matrix proteins attach between maternal and conceptus tissue

Invasion proper = the outer layer of the blastocyst, the trophoblast (seen above as the trophectoderm), proliferates and invades the endometrial lining

Question 23

spiral arteries bring pulsatile blood. what is the role of intervillous spaces?

Answer 23

these are spaces are called lacunae and fill with blood to reduce the force and speed of this pulsatile blood to increase chance of exchange

Question 24

how does the foetus exchange substances with the mother?

Answer 24

will some of the trophoblast remains nicely embedded in the endometrium as cytotrophoblasts, some continue to proliferate and form syncytiotrphoblasts that end up as villi and microvilli
these project through the outer layer to the pools of maternal blood and eventually become foetal capillaries

Question 25

in a mature placenta, what are the four layers between the foetal and maternal blood?

Answer 25

foetal capillary endothelium
mesenchyme
cytotrophoblast
syncytiotrophoblast

Question 26

explain how transport works form mother to foetus and vice versa

Answer 26

M to F -
glucose by f. diffusion
amino acids by secondary active transport
vitamins by active transport due to high demand
large molecules - receptor mediated endocytosis
the lacunae act as capillaries

F to M -
waste like creatine diffuse from amniotic fluid

Question 27

explain how the corpus luteum and placenta are involved in hormonal changes

Answer 27

corpus luteum is dominant at first, secreting oestrogen and progesterone in the first trimester to support the endometrium
HCG is produced by the trophoblast and is prevalent at day 8

at week 9 the placenta takes over as primary hormone source for the second trimester and produces human chorionic somatomammotropins

Question 28

what are hCS (human chorionic somatomammotropins) responsible for?

Answer 28

Coordinating ‘fuel’ by turning glucose to fatty acids for energy source
Ketone storage for neonate/foetus (to use as fuel)
Mammary gland development
Prog. synthesised from circulatory cholesterol

Question 29

how is the foetus involved in making progesterone?

Answer 29

maternal cholesterol is still the starting point for oestrogen, but to get to progesterone, the placenta doesn’t have all the enzymes it needs, so the foetus assists

Question 30

what happens in stage 0 of partuition?

Answer 30

quiescence -
uterus is insensitive to uterotonic hormones
progesterone supresses myometrial contractions
Braxton-hicks are preparation for actual labour proper contractions

Question 31

what happens ins stage 1 of partuition?

Answer 31

activation -
prep for labour = upregulation of the hypothalamic pituitary adrenal axis (more cortisol)
cortisol upregulates oestrogen in relation to progesterone, increasing contractility of the myometrium (don’t want a load of progesterone in labour as it supresses contractions)

Question 32

what does prostaglandin do, especially it’s effects on gene expression?

Answer 32

promotes gap junction formation to allow unimpeded flow of depolarisation

Also acts on cervix to soften, thin and dilate

Gene expression - contraction-associated proteins (CAPs) are uterotonic and have receptors for oxytocin to provide positive feedback mechanism, and prostaglandin receptors to produce more PGL in response to contractions

Cervical gene expression - enzymes to hydrolyse collagen matrix for the shortening/thinning/dilating

Question 33

summarise how the body has prepared for labour just before it begins - what is the Ferguson reflex?

Answer 33

oxytocin and PGL increased myometrial contractility, and increased myometrial responsiveness to themselves by causing production of CAPs
PGL results in cervical dilation and softening
gap junctions
Ferguson reflex = +ve feedback loop - contraction = more oxytocin = more contractions etc…

Question 34

what are the three parts of stage 2 of partuition?

Answer 34

labour:
1) dilation, relaxin hormone relaxes pelvic ligaments and widens cervix to prevent damage
2) expulsion of foetus
3) placental separation from the decidua

Question 35

what happens in stage 3 of partuition?

Answer 35

involution/recovery:
haemostasis (regulation of blood loss) vasoconstriciton of spiral arteries very important after blood loss from lacunae, reducing chance of haemorrhage

decreased placental oestrogen = myometrial atrophy = involution = reduction in size of the uterus

cervical remodelling to undo changes that occurred in labour

reestablishment of the endometrial cycle around 3-5 months later

Question 36

what makes up breast milk?

Answer 36

first milk = colostrum = supper high in fat and protein with loads of maternal antibodies
rest of milk is a fat emulsion high in sugars like lactose and proteins like casein and lactalbumin

Question 37

what structures are involved in lactation?

Answer 37

alveoli are the breast secretory units
there are contractile myoepithelial cells that help eject milk

Question 38

how do hormones effect the breasts during pregnancy?

Answer 38

oestrogen and progesterone result in growth and development, they also inhibit prolactin action on the breast as milk isn’t needed yet

oestrogen stimulates anterior pituitary to produce prolactin which is involved in breast development and lactogenesis

Question 39

hormones can have four postpartum effects in mammary glands - what are they and which hormones do what?

Answer 39

mamogenic - oestrogen promotes cell proliferation
lactogenic - PRL initiates milk production
galactokinetic - OT promotes myoepithelial contraction
galactopoietic - PRL and cortisol maintain milk production

Question 40

how do hormones interact with neurons in lactation?

Answer 40

most powerful stimulus for lactation is suckling
PRL inhibits dopamine release from hypothalamus as this would inhibit PRL if not
PRL downregulates GnRH to inhibit ovarian cycle - doesn’t completely stop it though you can still get pregnant