Hormones

• Endocrine glands

  • Ovaries (female only) - Produces oestrogen.
  • Testes (male only) - Produces testosterone.
  • Adrenal glands - Produces adrenaline (triggers fight or flight).
  • Pituitary gland - Main gland. Produces hormones in response to detections by the hypothalamus .
  • Thyroid gland - Produces thyroxine (regulates our temperature, heart rate and metabolism).
  • Pancreas - Produces insulin and glucagon (regulates blood sugar).
• The nervous system produces a faster response than the endocrine system, but is shorter lasting.
• Hormones are chemical messangers.
• Menstrual cycle

  FSH

  • Produced in Pituitary gland.
  • Matures egg.
  • Stimulates the release of Oestrogen.

  Oestrogen

  • Produced in Ovaries.
  • Builds up lining of the uterus.
  • Stimulates the release of LH, inhibits the secretion of FSH.

  LH

  • Produced in Pituitary gland.
  • Ruptures follicle, triggers ovulation.
  • Corpus Luteum remains.

  Progesterone

  • Produced in Ovaries.
  • Maintains lining of uterus.
  • Inhibits LH and FSH.

  
• Stages of Menstrual cycle

  1. (Days 1 - 4), the uterus lining breaks down, resulting in a 'period'.
  2. (Days 4 - 14), the uterus lining build back up to be thick and spongy.
  3. (Day 14), Ovulation happens (Egg is released by one of the ovaries).
  4. (Days 15 - 28), the Uterus lining is maintained, meaning that it is now ready for the arrival of a fertilised egg. If no fertilised egg arrives, the uterus lining begins to break down again, and the cycle repeats.

  
• Contraception is the act of preventing pregnancy.
• Contraception (PILL)

  Combined pill

  • Contains both oestrogen and progesterone.
  • By taking it every day, enough oestrogen builds up to inhibit the production of FSH, so that no egg matures.

  Progesterone pill

  • Stimulates the production of thick, sticky mucus, which is hard for the egg to penetrate.
  • Inhibits the production of FSH, so that no eggs mature.
  • Just as effective as the combined pill, but with fewer side effects.
• Contraception (Fertility)(Women)

  Contraceptive implant

  • Can last for 3 years.
  • Continually releases progesterone.

  Contraceptive injection

  • Contains progesterone.
  • Lasts up to 3 months.

  Contraceptive patch

  • Has to be changed once a week.
  • Steadily releases progesterone.
• Contraception (barrier)

  Diaphragm

  • Inserted into the vagina and sits at the entrance of uterus.
  • Prevents sperm from reaching and fertilising the egg.

  Coil

  • Inserted into the uterus.
  • Prevent the implanting of an embryo (fertilised egg).
  • Some also release progesterone.

  Condom

  • Often contains spermicide (kills the sperm).
  • Worn by the male, and prevents the sperm entering the female.
  • Protects against STIs (eg. chlamydia, gonorrhoea, HIV).
• Sterlisation - permanently infertile

  Men

  • Involves having the sperm ducts cut so that no sperm is released.

  Women

  • Involves having the fallopian tubes cut so that the egg cannot reach the uterus.
• Fertility treatments

  Fertility drugs

  • Contains a mixture of FSH and LH.
  • Boosting these can help mature and release an egg.

  In Vitro Fertilisation (IVF)

  • FSH and LH are given to stimulate the growth of lots of eggs.
  • Eggs are collected before being fertilised in a dish in a laboratory.
  • These grow into embryos, before being implanted into the women's uterus.
• Plant hormones

  Ethene

  • Ripens fruits.

  Gibberellins

  • Starts seed germination

  Auxins

  • Change growth patterns to allow roots and shoots to move either towards or away from a stimulus (change in conditions).
  • Responds to stimuli that involve directional growth (called tropisms).
• Uses of plant hormones

  Auxins

  • Selective weedkiller.
  • Rooting powder.

  Ethene

  • Used in food industry to control the ripening of fruit during sotrage and transport.

  Gibberellins

  • Used to promote flowering, increase fruit size and start seed germination.
• Tropisms

  Controlled by auxins.

  Phototropism

  • Positive = grows towards light.
  • Negative = grows away from light.

  Gravitropism

  • Positive = grows towards direction of gravity.
  • Negative = grows away from direction of gravity.
• Distribution of auxins in photoropsim

  1. One side of the shoot is more exposed to light.
  2. Auxins are redistributed so that there is a higher concentration on the shaded side.
  3. This results in cell elongation.
  4. In shoots, auxins promote elongation, however in roots it prevents elongation.