Thursday, 6 December 2012

A2 Biology: Homeostasis: Control of blood glucose concentration

If blood glucose concentration is too high it is detected by beta cells 
  • Beta cells (in islets of Langerhans) then secretes insulin into the blood
  • They target hepatocytes, muscles cells and other cells such as brain that have membrane bound receptors for insulin. Insulin binds to these receptors
  • Adenyl cyclase is activated in each cell and converts ATP to cAMP
  • this activates a series of enzyme reactions 
  • Glucose is converted into glycogen for storage/lipids
  • or used in respiration
  • glucose leave cells through specific channels
If blood glucose concentration is too low
  • This change is detected by alpha cells (in islets of Langerhans)
  • Alpha cells secrete the hormone glucagon
  • Targets cells are heptocytes which posses specific receptors for glucagon
  • glycogen is converted to glucose - glycogenolysis
  • glucose is made from amino acids and lipids - gluconeogenesis 

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