B11.5 - Human reproduction + Menstrual cycle Flashcards
which gland makes oestrogen
ovaries
oestrogen
-triggers development of secondary sexual characteristics
puberty changes in women
-growth spurt
-pubic and under arm hair
-breasts develop
-menstruation
ovulation
every 28 days a mature egg is released
what happens if the egg isn’t fertilised
14 days later it will be shed with a period
-all hormones drop
-lining pulls away and shed
FSH
causes egg to mature in ovary
LH
stimulates release of egg at ovulation time
function of oestrogen
builds up uterus lining
function of progesterone
maintenance of uterus lining
where is progesterone produced
empty egg follicle
menopause
eggs have run out
cannot have children
testosterone produced by
testes
testosterone effect
-pubic and underarm hair
-growth spurt
-voice breaks
-broader shoulders
-facial hair
which gland secretes FSH
pituitary
function of FSH
mature egg
-stimulate oestrogen production
increase of oestrogen
-inhibits FSH and increases LH
when does LH decrease
after ovulation
progesterone
-inhibits FSH + LH
-maintains uterus lining in case of implantation
why does progesterone inhibit FSH and LH
so that no other eggs are matured and released at the same time as implantation
-reduces risk of multiple pregnancies
contraception
prevents egg and sperm from meeting
or
prevents implantation of fertilised egg
Hormone based contraception
-low doses of oestrogen + progesterone
-to inhibit FSH
-prevent uterus lining from developing = prevents implantation
makes mucus in cervix thick = no sperm can enter
Hormone based contraception side effects
-raised blood pressure
- thrombosis (blood clotting)
-breast cancer
Progesterone only contraception
-more regularly taken
-prevent body hormones from overtaking = unexpected pregnancy
spermicides
kill sperm
not that effective
pro of implantation instead of pill
don’t have to remember to take it
barrier contraception - condoms
-prevents stds
-prevents sperm from entering
-can be unreliable as can split
IUD coil
contains progesterone - inhibits FSH
copper = stops implantation
IUD cons
-must be inserted by Dr
-could cause infections
abstaining
-not having sex at all or at times near ovulation
sterilisation
-cut sperm ducts (vasectomy)
or oviducts
-permanent
Infertility: lack of FSH
synthetic FSH and LH
IVF used if - oviducts
-oviducts are damaged or blocked by infection
IVF used if - donor
-donor egg has to be used
IVF used if - infertility
no obvious cause
IVF used if - sperm
-low sperm count
or isn’t matured sperm
so individual sperm is injected into egg
Process of IVF: stage 1
synthetic FSH and LH is injected into mother
-maturation of a number of eggs at once
Process of IVF: stage 2
-collect eggs from ovary and fertilise with sperm in lab
Process of IVF: stage 3
fertilised egg is kept in special solutions in warm conditions
-all growth of embryos
Process of IVF: stage 4
embryos are inserted into uterus
-bypasses faulty oviducts
Cons of IVF
-expensive
-health risks for mother
-emotionally and physically stressful
-multiple pregnancies = complications
