4.6.1 Reproduction Flashcards
(19 cards)
How does puberty work?
During teenage years, males and females become sexually mature which is controlled by various hormones. The sex cells start being produced/released and secondary sexual characteristics develop, which takes several years to complete.
What are the secondary sexual characteristics?
Females: Development of breast tissue, menstruation begins, hips widen
Males: Voice deepens, growth of penis and testes, sperm and semen production begin, gain of muscle tissue
Both: Public hair growth, underarm hair growth
Which hormones are responsible for these changes?
Oestrogen and testosterone are responsible for the development of the secondary sexual characteristics
Oestrogen is produced by the ovaries and testosterone is produced by the testes
Explain the Menstrual Cycle
- Every month the female body prepares for pregnancy
- This involves releasing an egg every 28 days and priming the uterus for implantation of the fertilised egg
- This process of releasing an egg in the ovary is called ovulation
- If pregnancy does not occur the body will start the process again
What 4 hormones control the Menstrual Cycle?
Luteinising Hormone (LH)
Follicle Stimulating Hormone
Oestrogen
Progesterone
When does Menstruation begin and how long does it last?
It begins at Day 1 of the cycle and lasts about 4 days
What happens at Day 4-14
The uterus lining gets thicker to prepare for a fertilised egg
How long is this uterus lining maintained for
It is maintained for 14 days (till 28th day)
On what condition does the cycle restart
If no fertilised egg is implanted
Explain the role of hormones in pregnancy
1) FSH is produced by the pituitary gland and causes egg to mature in a follicle
2) FSH stimulates ovary to release oestrogen
3) Oestrogen stimulates pituitary gland to release LH and also helps the uterus lining grow
4) Oestrogen causes pituitary gland to inhibit FSH
5) LH now causes the egg to be released by the follicle (ovulation) on Day 15
6) Progesterone is released by the remaining follicle and maintains the uterus lining
7) LH and FSH are inhibited by progesterone.
Name the hormones that can be used as hormonal contraceptives
Oestrogen and progesterone
What do oral hormonal contraceptives actually do to reduce fertility?
Oestrogen inhibits FSH production and so egg maturation is stopped and therefore egg isn’t released
Progesterone also inhibits FSH production as well as LH. It also causes thick cervical mucus to be produced. Therefore sperm can’t get beyond the cervix
Name non-oral hormonal contraceptives that can be used to prevent fertility
Skin patches, implants and injections
Explain what the non-oral hormonal contraceptives can actually do
Patches release oestrogen and progesterone (lasts for a week then replaced)
Implant releases progesterone (lasts for 3 years then replaced)
Injection contains projesterone
Explain how non-hormonal contraceptives can work
They work by preventing sperm and egg meeting (condoms or diaphragm)
Intrauterine devices are inserted into uteruses to kill sperm and prevent implantation of . They can also release progesterone to stop sperm.
Sterilisation by cutting fallopian tubes or sperm ducts - permanent procedure.
Not having sex when ovulating - very hard to work out when this is and unreliable
Why can women become infertile?
Some women may have low levels of FSH and LH
What can be done to treat infertility (basic)
FSH and LH can be injected to ensure eggs are matured and released
How does IVF treatment work?
IVF involves giving a mother FSH and LH to stimulate the maturation of several eggs.
The eggs are collected from the mother and fertilised by sperm from the father in a laboratory
The fertilised eggs develop into embryos.
At the stage when they are tiny balls of cells, 1 or 2 embryos arte inserted into the mothers uterus (womb).
