Regulating Blood Glucose Concentration (Edexcel GCSE Biology: Combined Science)

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Insulin & Blood Glucose Concentration

  • Blood glucose concentration must be kept within a narrow range, so it’s another example of homeostasis (like temperature control)
  • Blood glucose concentration is monitored and controlled by the pancreas
  • The pancreas is an endocrine gland (making and secreting hormones into the bloodstream) and it also plays a vital (but separate) role in digestion (making and secreting enzymes into the digestive system)
  • Eating foods containing carbohydrate results in an increase of glucose into the bloodstream
  • If the blood glucose concentration is too high, the pancreas produces the hormone insulin to bring it back down
    • Too high a level of glucose in the blood can lead to cells of the body losing water by osmosis, which can be dangerous

  • Insulin stimulates cells to take in glucose from the bloodstream (particularly liver and muscle cells)
  • In liver and muscle cells excess glucose is converted into glycogen (a polymer of glucose) for storage

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The Action of Glucagon

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  • If the blood glucose concentration is too low, the pancreas produces the hormone glucagon that causes glycogen to be converted into glucose and released into the blood.
  • Glucagon and insulin interact as part of a negative feedback cycle to control blood glucose (sugar) levels in the body:
    • Insulin is produced when blood glucose rises and stimulates liver and muscle cells to convert excess glucose into glycogen to be stored – this reduces the blood glucose level
    • Glucagon is produced when blood glucose falls too low and stimulates liver and muscle cells to convert stored glycogen into glucose to be released into the bloodstream – this increases the blood glucose level

Negative feedback regulation of blood glucose levels, IGCSE & GCSE Biology revision notes

Negative feedback regulation of blood glucose levels

Examiner Tip

The terms glucagon and glycogen are very often mixed up by students as they sound similar. Remember:

  • Glucagon is the hormone
  • Glycogen is the polysaccharide glucose is stored as

Learn the differences between the spellings and what each one does so you don't get confused in the exam!

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Lára

Author: Lára

Expertise: Biology Lead

Lára graduated from Oxford University in Biological Sciences and has now been a science tutor working in the UK for several years. Lára has a particular interest in the area of infectious disease and epidemiology, and enjoys creating original educational materials that develop confidence and facilitate learning.