Homeostasis & Response - Animal & Plant Hormones Flashcards
what is the main reproductive hormone in men
testosterone. produced in testes and stimulates sperm production
what is the main reproductive hormone in females
oestrogen. produced in ovaries
what are the 4 stages of the menstrual cycle
- lining of uterus breaks down ( bleeding starts about 4 days)
- lining of uterus builds up ( from day 4 to 14)
- egg is released ( called ovulation (day 14))
- uterus lining maintained ( until day 28)
what does the follicle stimulating hormone do and where is it made
causes egg to mature in one of the ovaries in a structure called a follicle. also stimulates ovaries to produce oestrogen
produced in pituitary gland
what does luteinising hormone do and where is it made
stimulates ovulation at day 14
what does oestrogen and progesterone do
growth and maintenance of uterus lining. oestrogen stimulates the release of LH and inhibits FSH.
progesterone is produced in ovaries by the remains of the follicle after ovulation. it maintains the lining of the uterus so when progesterone levels fall, the lining breaks down. also inhabits release of LH and FSH
how can oestrogen be used to reduce fertility
if taken daily it keeps oestrogen levels permanently high so FSH production will be inhabited which will stop egg maturation and therefore release.
how can progesterone be used to reduce fertility
stimulating production of thick cervical mucus which prevents sperm getting through and reaching an egg
it can inhabit egg maturation and therefore the release of an egg too.
benefits of the combined oral pill
over 99% effective
reduced risk of getting some types of cancer
problems with combined oral pill
extremely slight chance of getting pregnant
side effects like headaches, nausea, irregular bleeding and fluid retention
doesn’t protect against STDs
what is a contraceptive patch
contains oestrogen and progesterone. 5x5cm that stuck to the skin that lasts one week
what is a contraceptive implant
inseted under skin of arm. releases a continuous amount of progesterone which stops ovaries releasing eggs. Can last for 3 years
what is a contraceptive injection
contains progesterone and last 2 to 3 months
what is a diaphragm
a plastic cup that fits over cervix to form a barrier. has to be used w a spermicide
what is a intrauterine device
t shaped device inserted into uterus to fill sperm and prevent implantation of a fertilized egg. some release progesterone and there are copper ones that prevent sperm surviving
surgical methods of contraception
sterilization- cutting or tying fallopian tubes or the sperm duct in a male. parament but small chance tubes can re-join
what is a natural method of contraception
avoiding seggs on days when woman is most fertile
abstinence- not having seggs
how can fertility drugs increase fertility
woman who’s fsh level is too low for egg to mature, the hormones FSH and LH can be injected to stimulate egg maturation and release into the ovaries
problems with fertility drugs
dont always work it can become expensive
too many eggs can be stimulated so too many babies
In Vitro Fertilization
FSH & LH given to woman to stimulate maturation of multiple eggs
eggs collected from ovaries and fertilised in lab with mans sperm
grow into embryos in lab incubator
one or two transferred into uterus
cons of IVF
multiply births can happen which makes risks
low success rate 26% so stresful and upsetting
physically stressful e.g. vomiting dehydration and abdominal pain
how has micro tools improved ivf success rate
use on egg and sperm under microscope and remove single cells from embryo for genetic testing
how has time lapse imaging improved ivf
(using a microscope and camera built into incubator) so embryos can be monitored to identify those more likely to succeed
social and ethical issues with ivf
unused embryos get destroyed
genetic testing makes ppl think it could lead to selection of preferred characteristics
where is thyroxine made and what does it do
thyroid gland regulates basal metabolic rate also stimulating protein synthesis released in response to TSH which is released from pituitary gland released on negative feedback loop
where is adrenaline released from and what does it do
adrenal glands, just above kidney
in response to stressful or scary situations
brain sends nervous impulses to adrenal glands
increased oxygen supply and glucose to muscle and increased heartrate
auxin
controls growth, phototropism, gravitropism.
produced in tips of shoots and roots and moves backwards to stimulate the cell elongation process. so if shoot is removed, no auxin is available so shoot may stop growing
what is phototropism
plant growth in response to light
what is gravitropism
plant growth due to gravity
why do shoots grow towards light
more auxin accumulates on the side that’s in shade so it elongates faster on the shaded side so shoot bends towards the light
why do shoots grow away from gravity
gravity causes auxin to go to lower side of shoot when horizontal so it will grow faster on the lower side, causing it to bend upwards
why do roots grow towards gravity
when a root is horizontal, more auxin will accumulate on its lower side. in a root, extra auxin inhabits growth so the cells on top will elongate faster so the root bends downwards
how can auxins be used for killing weeds
weeds in grass and narrow crop usually have broader leaves. weed killer with auxins which only affect the broad leave plants disrupt their normal growth patterns which soon kills them
how are auxins used in rooting powder to grow cuttings
rooting power contains auxins that when added to cuttings will produce rapid roots so the cutting can grow in the soil as a new plant. growers can produce clones like this quickly
how are auxins used to grow cells in tissue cultures
auxins added to growth medium along w nutrients to stimulate cells to divide to produce shoots and roots
what are gibberellins
growth hormone in plants that stimulates germination, stem growth and flowering
how can dormancy be altered
seeds can be treated with gibberellins to change wen they germinate. also make sure all seeds in a batch germinate at the same time
how can flowering be induced
plants treated with gibberellins will flower without any change in the environment. gibberellins can also be used to make bigger flowers
why may gibberellins be used to grow larger fruits
seedless variants do not often grow as big
what does ethene naturally do to a plant
influences growth by controlling cell division and stimulates enzymes that cause fruit to ripen
what can ethene be used for commercially with plant s
speed up ripping so can be picked when unripe and ripened on way
ripening can be delayed by adding chemical that blocks ethene or react with it to remove it from the air so the fruit can be stored for longer
