11 - Hormonal Coordination

• Endocrine System - glands that secrete hormones into the bloodstream
• Hormones are produced in the endocrine glands
• Types of endocrine glands:

  • Pituitary
  • Thyroid
  • Pancreas
  • Adrenal
  • Ovaries
  • Testes
• Pituitary

  • control growth and rate of metabolism
  • make oestrogen and testosterone
  • release ADH
  • in the brain
• Thyroid

  • controls rate of metabolism
  • in throat
  • releases TSH
• Pancreas

  • controls level of glucose in blood
  • releases insulin and glucagon
• Adrenal

  • prepares body for stressful situations
  • in chest
  • releases adrenaline
• Ovaries:

  • releases oestrogen
• Testes

  • releases testosterone
• Negative Feedback - A system that responds to a change in the environment by returning the system to its original state
• Negative Feedback with glucose:

  • low - glucagon released
  • glycogen broken down in our liver into glucose
  • amino acids broken down
  • high - insulin released
  • helps cells absorb glucose quicker
  • glucose converted in glycogen in liver
• Type 1 diabetes - pancreas doesn't make enough insulin
• Type 2 diabetes - body stops responding to insulin
• Thyroxine hormone:

  • produced in thyroid gland in neck
  • uses iodine from diet to produce it
  • control metabolic rate
  • important for growth
  • If too high, TSH level fall
• Hormones in menstrual cycle:

  • FSH
  • LH
  • Progesterone
  • Oestrogen
• FSH - causes egg to mature

  • secreted by pituitary gland
  • stimulates production of oestrogen
• LH - stimulates release of egg

  • once ovulation occur, LH fall
• Oestrogen and Progesterone stimulate build up and maintenance of the uterus lining
• High level of oestrogen inhibits the production of FSH and stimulates release of LH
• Progesterone - maintains pregnancy

  • inhibit FSH and LH
• Plant Hormones:

  • Auxins
  • Gibberellin
  • Ethene
• Plant roots are sensitive to gravity and grow down in direction of gravity
• Plant shoots are sensitive to gravity and light and grow toward light but against gravity
• Phototropism - growing towards to/away from light
• Geotropism - growing with/against gravity
• Auxin - makes plants grow

  • accumulate of shaded area so shaded side grows quicker than exposed side so plant bends towards light
• Ethene - stimulates ripening of plant
• Gibberellin - controls dormancy in plants