Endocrine system

• Hormones are released by organs called glands
• Glands

  Pituitary gland

  Thyroid

  Pancreas

  Adrenal glands

  Ovaries

  Testes
• Blood carries hormones to their target organs where they produce a specific effect
• Effects of endocrine system are produced slower than the nervous system but they last longer
• Pituitary gland


  Known as master gland

  Produces hormones that effect many target organs

  Can stimulate other glands to release more hormones
• Pancreas


  Monitors and controls blood glucose levels

  If levels too high releases a hormone called insulin

  if levels too low releases a hormone called glucagon
• Insulin’s causes glucose to move out of blood into cells, reduces level of glucose in the blood

  Can also cause liver and muscle cells to convert glucose into glycogen
• Glucagon causes liver and muscle cells to convert glycogen into glucose, then the glucose moves out of the cells and into the blood
• Diabetes is a condition where blood glucose levels sty high after eating
• type 1 diabetes


  Pancreas doesn’t produce enough insulin
• Type 1 treatments

  Injecting patients with insulin

  Controlling amount of carbs the patient eats

  No cure
• Type 2 diabetes


  Cells dont respond to insulin properly
• Type 2 treatments

  Exercise

  Controlling amount of carbs eaten
• Negative feedback

  Reduces the level of something if it rises

  Increases the level of something if it falls
• Examples of negative feedback


  effects of insulin and glucagon on blood glucose concentration
• Thyroxine

  Produced in thyroid gland

  Hormone essential to growth and development

  Controls basal metabolic rate
• Adrenaline

  Produced in adrenal glands

  Affects how animals respond to potentially dangerous situations

  Cause heart and breathing rate to increase, so more oxygen and glucose delivered to brain and muscles

  More energy
• Body can control how much water and ions and urea is lost in urine
• The liver and kidneys are organs involved in the production of urine, the bladder stores it
• The kidneys remove excess water, ions and urea from the blood by filtering it
• Filtration of the blood happens in structures called kidney tubules
• selective reabsorption


  When kidneys filter the blood, some usefuel substances are filtered out

  Kidney tubules must reabsorb these useful substances
• Selective reabsorbtion prevents the glucose, water and ions from being lost in the urine
• ADH is a hormone that effects the function of the kidneys
• ADH makes the parts of the kidney tubules that reabsorb water more permeable so they can reabsorb more water
• ADH is released by the pituitary gland
• The liver controls the amount of amino acids in the body
• The liver converts excess amino acids into ammonia which is toxic so the liver immediately converts ammonia into urea so it can leave the body in urine