Dictionary > Glycogenolysis

Glycogenolysis

Definition
noun
The metabolic process of breaking down stored glycogen in liver into glucose subunits (i.e. glucose-6-phosphate) using inorganic phosphate for use in energy metabolism
Supplement
Glycogenolysis is the process of breaking down stored glycogen in the liver so that glucose may be produced for use in energy metabolism. The process makes use of an inorganic phosphate. Two key enzymes in glycogenolysis are glycogen phosphorylase and debranching enzyme. Glycogen phosphorylase catalyzes the release of glucose-1-phosphate from the terminal alpha-1,4-glycosidic bond. Debranching enzyme lops off the branches.1
Glycogenolysis occurs in the hepatocytes. Glycogen in the liver is broken down to provide a source of blood glucose especially during in between meals when blood glucose level is low. The opposite of glycogenolysis is glycogenesis, which is the process wherein glucose molecules are added to chains of glycogen for storage. Glycogenolysis and glycogenesis are regulated by the effects of hormones, glycagon and insulin. Glucagon stimulates glycogenolysis; insulin inhibits it and favors glycogenesis. Thus, one of the main functions of glycogenolysis is for the regulation of glucose concentration in the bloodstream, however, in the short term only (see gluconeogenesis for long term. The pancreatic alpha cells secrete glucagon in response to low blood glucose, for instance as a result of moderate exercise or fasting.
Glycogenolysis also takes place in myocytes, particularly, during the fight-or-flight response. The hormone that regulates it is epinephrine. Glucogenolysis in myocytes differ from that in hepatocytes in a way that the former generally does not lead to the release of glucose into the bloodstream but stays within the myocyte for glycolysis.
Other regulators of glycogenolysis include cortisol, human growth hormone, and intracellular enzymes.1
Compare:

See also:

  • glycogen
  • glucose
  • glycogen
  • insulin
  • Reference(s):

    1 Naish, J. & Court, D. S. (2014). Medical Sciences. Elsevier Health Sciences. p. 75 -76.


    You will also like...

    Biological Cell Defense
    Biological Cell Defense

    Organisms employ different strategies to boost its defenses against antigens. Humans have an immune system to combat pat..

    Wart-like leaf galls on grape leaves
    Plant Cell Defense

    Plants protect themselves by releasing hydrogen peroxide to fight against fungal invasion. Another way is by secreting c..

    The process of photosynthesis
    Photosynthesis – Photolysis and Carbon Fixation

    Photosynthesis is the process that plants undertake to create organic materials from carbon dioxide and water, with the ..

    Kidneys
    Kidneys and Regulation of Water and Inorganic Ions

    The kidneys are responsible for the regulation of water and inorganic ions. Read this tutorial to learn about the differ..

    Genetic engineering
    Genetic Engineering Advantages & Disadvantages

    This tutorial presents the benefits and the possible adverse eventualities of genetic engineering. Know more about this ..

    Early Mammals on Earth
    Early Mammals on Earth

    The Earth's ecosphere was rapidly changing and throwing up a wide range of ecological niches that new adaptive organisms..