Puberty & Menstrual Cycle

• puberty

  development of secondary sex characteristic
• main male reproductive hormone

  testosterone
• main female reproductive hormone

  oestrogen
• menstrual cycle

  a female reproductive cycle involving changes in the uterus
• 4 hormones menstrual cycle controlled by

  • FSH
  • LH
  • oestrogen
  • progesterone
• 4 stages of menstrual cycle

  • menstruation
  • proliferation
  • ovulation
  • fertilisation
• menstruation

  • days 1-7
  • egg is not released
  • uterus breaks down
  • main hormone - FSH
  • affect of hormone - inhibits progesterone, stimulates 1 egg cell & oestrogen
• proliferation

  • days 4-14
  • egg is mature but not released
  • lining builds up in uterus
  • main hormone - oestrogen
  • affect of hormone - inhibits FSH production, stimulates uterus to thicken & LH production
• ovulation

  • day 14
  • egg is released
  • uterus lining is thick
  • main hormone - LH
  • affect of hormone - inhibits oestrogen production, causes release of ovum, stimulates progesterone
• fertilisation

  • days 15-18
  • egg released
  • uterus thick, fertilsed & maintained
  • main hormone - progesterone
  • affect of horrmone - inhibits FSH & LH production, maintains uterus lining
  • NO FERTILISATION - uterus broken down, stimulates FSH production
• hormones & control of menstrual cycle

  • pituitary gland secretes FSH which causes an egg to mature
  • FSH causes the ovary to secrete oestrogen
  • oestrogen causes the pituitary gland to secrete LH which causes the egg to be released from the ovary
• contraception

  used to prevent pregnancy & the spread of sexually transmitted diseases
• contraception can be hormonal or non-hormonal
• hormonal contraceptives

  • pills
  • patches
  • injections
• non-hormonal contraceptives

  • condoms
  • diaphragms
  • IUD's
• hormones used in contraception

  • oestrogen
  • progesterone
• oestrogen is used in contraception as it prevents egg release, inhibits FSH production and stops egg from maturing
• progesterone is used in contraception as it stimulates prodcution of thick cervical mucus, prevents sperm from getting through and inhibits egg maturation/release
• oral contraceptives (pill)

  • stops FSH production
  • contains oestrogen & progesterone
  • advantage - reduces risk of cancer/STD's
  • disadvantage - 99% effective
• contraceptive implant

  • slow release of progesterone
  • small device , injection or patch inserted under skin
  • advantage - can have sexual contact without worry
  • disadvantage - 95% effective
• barrier methods (condoms/diaphragm)

  • prevents sperm from meeting egg or uterus
  • diaphragm - shallow plastic cup fitted into cervix condom - something over penis
  • advantage - protects against STD's
  • disadvantage - not 100% effective/ unreliable
• IUD

  • produces progesterone & thick mucus to prevent sperm to enter
  • device inserted into uterus
  • advantage - prevents pregnancy/ long lasting
  • disadvantage - 85% effective / pain can be experienced
• spermicidal agent

  • kills sperm on entrance into vagina
  • advantage - readily available/no need for prescription
  • disadvantage - allergic reactions/irritation
• female sterilisation

  • prevents egg from travelling down the oviduct
  • cutting or tying up the oviduct
  • advantage - permanent procedure, 100% effective
  • disadvantage - surgical complications
• male vasectomy

  • sperm cant get out of penis
  • spermduct is tied up or cut
  • advantage - permanent procedure, 100% effective
  • disadvantage - surgical complications
• hormones can also be used to increase fertility
• hormones used to increase fertility

  • FSH
  • LH
• FSH is used to increase fertility as it causes egg to mature and LH is used for egg release
• fertility drug

  • advantage - helps lots of women get pregnant when theyy couldnt conceive naturally
  • disadvantage - doesnt always work, unexpected multiple pregnancies
• IVF also helps couples to have children
• process of IVF

  • mother is given FSH & LH to stimulate the eggs
  • the eggs are collected from the mother
  • the eggs are then fertilised with the fathers sperm in laboratory
  • fertilised eggs develop into embryos
  • when they become tiny balls of cells they are inserted back into the mothers uterus
• IVF

  • advantages - give an infertile couple a child
  • disadvantages - side effects from hormones, multiple births risky for both mother and child
• IVF has ethical issues as it results in unused embryos which could be a potential human life and that IVF could also lead to selection of preferred characteristics