Homeostasis

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Homeostasis

• L.O to define homeostasis and explain how
  homeostasis occurs
• Starter Year 11 homeostasis quiz what can you
  remember from two years ago??!

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Homeostasis

• Definition
• Homeostasis is maintenance of a constant internal
  environment within a living organism.
• Homeo same Stasis state

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Negative Feedback
A series of changes that result in a substance
being restored its normal / optimum level. Can
you put the parts of a negative feedback system
in the correct order? Then match up the sections
with their correct description. Ask me to check
before you glue them down! Once youve done, try
to write an example of negative feedback next to
each section. E.g a waterbath getting too hot
what would happen?
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Negative Feedback
A series of changes that result in a substance
being restored its normal / optimum level.
Section Set Point / Optimum Level Input Receptor Controller Effector Output Feedback Loop
Description The normal /optimum level A detectable change Measures the level of change Receives and controls info from receptor Carries out the change needed to restore to norm System is returned to normal / optimum level Informs the receptor about the changes made by the effector
Example Waterbath on at 40c Water temperature rises to 42c Thermostat detects change Heating element is turned off Water temperature falls
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What needs to be regulated by such a control
system?
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Examples of Homeostasis(in a quiz stylee!)
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Examples of Homeostasis(in a quiz stylee!)
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Examples of Homeostasis(in a quiz stylee!)
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Examples of Homeostasis

1. Glucoregulation keeping blood sugar levels
   constant
2. Thermoregulation keeping body temperature
   constant at ?...c
3. Osmoregulation keeping water and ion levels
   constant

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Osmoregulation

• If your blood water conc falls

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Osmoregulation

• If your blood water conc falls
• This is detected by osmoreceptors in the
  hypothalamus

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Osmoregulation

• If your blood water conc falls
• This is detected by osmoreceptors in the
  hypothalamus
• Pituitary gland releases ADH (anti-diuretic
  hormone) into the blood

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Osmoregulation

• If your blood water conc falls
• This is detected by osmoreceptors in the
  hypothalamus
• Pituitary gland releases ADH (anti-diuretic
  hormone) into the blood
• This makes your kidney tubules more permeable to
  water

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Osmoregulation

• If your blood water conc falls
• This is detected by osmoreceptors in the
  hypothalamus
• Pituitary gland releases ADH (anti-diuretic
  hormone) into the blood
• This makes your kidney tubules more permeable to
  water
• So you absorb more water!

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Osmoregulation

• However
• Alcohol interferes and reduces the effect of ADH
  what consequences does this have on your body??
• Interestingly
• Boxers and jockeys who want to lose weight use
  diuretic drugs how would this work??