negative feedback and its importance in biology

control of blood glucose concentration
1. pancreas detects blood glucose concentration is too high
  1. 1. beta cells secrete insulin and alpha cells stop secreting glucagon
  2. 2. insulin binds to receptors on liver and muscle cells
  3. 3. cells take up more glucose, glycogenesis is activated, cells respire more glucose
  4. 4. less glucose in the blood
2. pancreas detects blood glucose concentration is too low
  1. 4. cells release glucose into the blood
  2. 3. glycogenolysis is activated, gluconeogenesis is activated, cells respire less glucose
  3. 1. alpha cells secrete glucagon and beta cells stop secreting insulin
  4. 2. glucagon binds to receptors on liver cells
control of blood water potential
1. low water potential in the blood
  1. 1. the drop in water content is detected by osmoreceptors in the hypothalamus
  2. 2. the posterior pituitary gland releases more ADH into the blood
  3. 3. the DCT and collecting duct then become more permeable so more water is reabsorbed into the blood by osmosis
  4. 4. a small amount of highly concentrated urine is produced and less water is lost
2. high water potential in the blood
  1. 1. the rise in water content is detected by osmoreceptors in the hypothalamus
  2. 2. the posterior pituitary gland releases less ADH into the blood
  3. 3. less ADH means that the DCT and collecting duct become less permeable so less water is reabsorbed into the blood by osmosis
  4. 4. a large amount of dilute urine is produced and more water is lost
control of heart rate and blood pressure
1. high blood pressure, O2 and pH levels and low CO2 levels
  1. 1. baroreceptors detect high blood pressure and chemoreceptors detect chemical change in the blood
  2. 2. impulses are sent to the medulla which sends impulses along parasympathetic neurones which secrete acetylcholine which binds to receptors on the SAN
  3. 3. heart rate slows down and decreases, reducing blood pressure and returning O2, CO2 and pH levels back to normal
    1. negative feedback prevents damage to artery walls, atheromas, blood clots and myocardial infarctions
2. low blood pressure, O2 and pH levels and high CO2 levels
  1. 1. baroreceptors detect low blood pressure and chemoreceptors detect chemical change in the blood
  2. 2. impulses are sent to the medulla which sends impulses along sympathetic neurones which secrete noradrenaline which binds to receptors on the SAN
  3. 3. heart rate speeds up and increases, increasing blood pressure and returning O2, CO2 and pH levels back to normal
    1. negative feedback prevents damage to artery walls, atheromas, blood clots and myocardial infarctions
homeostasis
1. the maintenance of a constant internal environment despite fluctuations
  1. receptors to detect when levels are not at the normal level
  2. the info is then communicated via the nervous or hormonal system
  3. effectors then respond to counteract the change to bring the level back to normal
    1. the mechanism that restores the level to normal is negative feedback
  4. this is vital for cells to function noramlly and stop them being damaged

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negative feedback and its importance in biology

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	Created by freya hinks over 7 years ago