menstrual cycle and pregnancy Flashcards
day 1 of menstrual cycle
menstruation starts
uterus lining breaks down for about 4 days
day 4 to 14 ( stage 2 )
uterus lining builds up again into a thick and spongy layer full of blood vessels, ready to recieve a fertilised egg
day 14 (stage3)
egg develops and is released from ovary at day 14 ( ovulation)
stage 4 , day 14-28
wall is then maintained until day 28, if no fertilised egg has landed on the uterus wall by day 28, spongy lining starts to break down and whole cycle starts again
FSH
follicle stimulating hormone
FSH produced in
pituitary gand
what does FSH do (2)
- causes egg to mature in one of the ovaries in a structure called a follicle
- stimulates ovaries to produce oestrogen
oestrogen produced in
ovaries
what does oestrogen do
causes lining of uterus to grow
stimulates release of LH
LH
leutanising hormone
LH produced by
pituitary gland
what does LH do
stimulates release of egg at day 14 ( ovulation)
progesterone produced in
ovaries
what does progesterone do
maintains lining of the uterus during second half of cycle
inhibts release of LH and FSH
what does amniotic fluid do
protects embryo against knocks and bumps
where is amniotic fluid held
in the amniotic membrane
placenta is an efficient exchange surface because (4)
- A large surface area
- Villi, which further increase the surface area of the placenta
- A thin wall for efficient diffusion
- Good blood supply
once an ovum has been fertilised, it develops into a ___ and implants in the ___
embryo
uterus
once the embryo has implanted, the ____ develops
placenta
what does the placenta do
allows the blood of the embryo and mother get very close to allow the exchange of food, oxygen and waste
