hormones

• Thyroid gland

  Produces thyroxine when stimulated
• Brain

  • Contains hypothalamus, which controls pituitary gland
• Pituitary gland hormones

  • ADH
  • LH
  • FSH
• Adrenal gland

  Produces adrenaline to prepare body for fight-or-flight response
• Adrenaline production increases

  Increases blood sugar level and directs blood to muscles and brain
• Pancreas

  Produces insulin to control blood sugar level
• Ovaries

  Produce oestrogen and progesterone to control menstrual cycle
• Testes

  Produce testosterone which causes changes at puberty and stimulates sperm production
• Hormones

  Part of the endocrine system, secreted into bloodstream to reach all parts of the body
• Hormones control long-term processes which are not consciously controlled, such as growth and metabolism
• Negative feedback mechanism

  1. Conditions in body change

  2. Hormone released

  3. Corrective mechanism activated

  4. Conditions return to normal

  5. Corrective mechanism turned off
• Menstrual cycle

  1. FSH causes eggs to mature

  2. LH triggers egg release

  3. Oestrogen builds up uterine lining

  4. Progesterone maintains uterine lining

  5. Uterine lining falls, triggering menstruation
• Non-hormonal contraceptive methods

  • Condom
  • IUD
  • Cervical cap
• Causes of infertility

  • Blocked fallopian tubes
  • Lack of mature eggs
  • Low sperm production
• Phototropism

  Plant growth towards light
• Geotropism

  Plant growth in response to gravity
• Auxin

  Plant hormone that stimulates growth, inhibits weeds, promotes fruit development, and regulates ripening
• Gibberellins

  Plant hormones that control dormancy, convert starch to sugar, and promote growth
• FSH causes eggs to mature 

  FSH stimulates ovaries to produce oestrogen

  LH stimulates the egg to be release
• Oestrogen and progesterone: are used in hormonal contraceptives

  to inhibit LH and prevent ovulation

  to inhibit FSH and prevent egg maturation and also thicken mucus
• Hormones that stimulate the ovaries are LH and FSH
• Auxins stimulate cell/plant growth
• Auxins can be used in weed killers, rooting powders, and to promote growth in tissue cultures
• The endocrine system is made up of glands that release hormones.

  These hormones act as chemical messengers that allow communication throughout the body.
• Adrenaline stimulates liver cells to break glycogen down into glucose and release it into the bloodstream.
• Auxin accumulates on the shady side of the plant
• When the eye's lens is short and fat (more rounded) it refracts light more
• Ethene stimulates fruit to ripen, so it can be used in the food industry to control the ripening of fruit during storage and transport.
• 1. Auxins stimulate plant cells to divide and grow. 
  2. If large amounts of auxins are added to plants, it can disrupt their growth process by overstimulating them. 
  3. This can kill the plant.