Reproductive system Flashcards
what is testosterone
produced by the testes – is the main male reproductive hormone and it stimulates sperm production
what is oestrogen
produced by the ovaries – is the main female reproductive hormone.
what happens during the menstrual cycle
- every 28 days, ovulation takes place
- in preparation for this, the uterus lining becomes thick and spongy
- the egg now makes its way down to the uterus
- if sperm is present the egg can be fertilised, if this happens it can implant into the uterus walls and develop into a baby
- if not, both the egg and the uterus lining are released
what is the role of FSH ( Follicle- stimulating hormone)
Causes an egg to mature in an ovary.
Stimulates the ovaries to release oestrogen
what is the role of Oestrogen
- Repairs, thickens and maintains the uterus lining. -
Stimulates the pituitary gland to release LH. - Stops FSH being produced (so that only one egg matures in a cycle)
what is the role of LH (Luteinising hormone)
Triggers ovulation (the release of a mature egg)
Stimulates the release of an egg
what is the role of progesterone
Maintains the lining of the uterus during the middle part of the menstrual cycle and during pregnancy
- inhibits the release of fsh and lh
why doesn’t menstruation happen during pregnancy
the placenta produces progesterone. This maintains the lining of the uterus during pregnancy and means that menstruation does not happen.
what happens on day 1 of the menstruation cycle
uterus lining breaks down for about 4 days
what happens on stage 2 of the menstruation cycle
uterus lining builds up again, from day 4 to 14, into a thick spongy layer full of blood vessels, ready to recieve a fertilised egg
what happens on stage 3 of the mestruation cycle
an egg develops and is released from the ovary at day 14, this is OVULATION
what happens on stage 4 of the menstrual cycle
the wall of the ovary is well maintained for about 14 days, if no fertilised egg has landed on the uterus wall, the spongy lining starts to break down, cycle starts again
how can oestrogen be used as a contraceptive pill
- prevents the release of an egg, inhibits the production of FSH
how can progesterone be used as a contraceptive pill
- stimulates the production of thick mucus which prevents sperm getting through and reaching an egg
benefits of contraceptive pill
- over 99% effective
- can reduce the risk of certain cancers
disadvantages of contraceptive pill
side effects like nausea and headaches
- mood swings
- changes in blood pressure due to amounts of oestrogen
- doesn’t protect against STDs
- has to be taken everyday
non hormonal methods of contraception
- condoms
- IUD- T shaped device inserted into uterus to kill sperm and prevent implantation of fertilised egg
- abstinence, refraining from sex completely
- contraceptive patch
- contraceptive implant
- spermicide
- diaphragm (plastic cup) that fits over the cervix to form a barrier, has to be used with spermicide
example of a permanent barrier
STERILISATION, VASECTOMY
Risks of non- hormonal barriers
Condoms are easy and quick to use, but sometimes they can tear or rip.
Diaphragms need to be put in just before sex and left in several hours afterwards.
Spermicidal agents can be added to other physical barriers such as condoms, but some people can have allergic reactions to these.
Abstaining can be used successfully, but if the timings are not accurate the chance of pregnancy is high.
Surgical methods cannot be reversed, and is considered permanent.
how can hormones be used to INCREASE fertility
low amounts of hormones LH and FSH can cause eggs to not mature, these can be given to a woman to stimulate ovulation
- this combination will cause the woman to ovulate more than usual, increasing her chances of becoming pregnant through sexual intercourse
pros and cons of hormones being used to increase fertility
pros- helps women become pregnant
cons - doesnt always work, can be expensive, too many eggs could be stimulated, resulting in unexpected multiple pregnancies, e.g twins
what does IVF (In vitro fertilisation) involve
- woman is treated with FSH and LH
- eggs are collected from a womans ovaries then fertilising them in a lab using the mans sperm
- can also involve a technique called INTRA-CYTOPLASMIC SPERM INJECTION, where the sperm is injected directly into an egg
- the fertilised eggs then grow into embryos
- once the embryos are tiny balls of cells, one or two are transferred to the womans uterus to improve chance of pregnancy
why are LH and FSH given before IVF
- to stimulate several eggs to mature ( so more than one egg can be collected)
risks of IVF
- multiple births can happen
- success rate of IVF low, 26% in UK, making the process very stressful and upsetting if it ends in multiple failures
- physically stressful, could cause abdominal pain, dehydration, vomiting
advantages of IVF
It allows people to have babies of their own, who otherwise can’t due to a variety of reasons.
It has a safe track record and has been used since 1978.
- The embryos can be screened for genetic diseases, which is important for families that already have an affected child. Only unaffected embryos are used.
- Unused eggs can be used for research or donated to other couples.
Ethical issues with IVF
- unused embryos are destroyed, could be a human life
- genetic testing could lead to selection of preferred characteristics like gender or eye colour
What do hormones do
they travel in the bloodstream and trigger effects in specific target organs
what happens during puberty
reproductive hormones cause secondary sexual characteristics to develop such as pubic hair
what is ovulation
process of ovaries releasing an egg
how do the hormones interact w eachother step by step
- FSH is released by the pituitary gland
- FSH travels in the blood to the ovaries where it causes an egg to mature
- at the same time, FSH triggers the ovaries to make oestrogen
- oestrogen stops pituitary gland from releasing fsh
- pituitary gland releases LH
- ovary produces progesterone
why does progesterone stop the pituitary gland from releasing fsh and lh
to prevent any more eggs from maturing or being released
what are contraceptives
things that prevent fertilisation
advantages of using non oral contraceptives such as the iud
- more convenient than taking daily pill
- patch lasts abt a week
- injection lasts about 13 weeks
advantages of barrier methods
condoms can reduce the risks of sti
how could condoms be made more effective
using spermicide gel
