Podcast
Questions and Answers
What triggers the release of insulin into the bloodstream?
What triggers the release of insulin into the bloodstream?
What is one of the actions of insulin in the body?
What is one of the actions of insulin in the body?
Which hormone is produced by the B-cells of the islets of Langerhans?
Which hormone is produced by the B-cells of the islets of Langerhans?
Which process is suppressed by insulin?
Which process is suppressed by insulin?
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What effect does insulin have on gluconeogenesis?
What effect does insulin have on gluconeogenesis?
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What is the primary function of glycogen phosphorylase in glycogenolysis?
What is the primary function of glycogen phosphorylase in glycogenolysis?
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Where does glycogenolysis primarily occur in the body?
Where does glycogenolysis primarily occur in the body?
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What molecule is primarily produced during glycogenolysis?
What molecule is primarily produced during glycogenolysis?
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What is the role of the debranching enzyme in glycogenolysis?
What is the role of the debranching enzyme in glycogenolysis?
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What is formed when four glucose units remain near an α(1,6) branch point during glycogenolysis?
What is formed when four glucose units remain near an α(1,6) branch point during glycogenolysis?
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What stimulates the synthesis of glucagon?
What stimulates the synthesis of glucagon?
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Which cells produce glucagon in the pancreas?
Which cells produce glucagon in the pancreas?
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What is one of the primary actions of glucagon in the body?
What is one of the primary actions of glucagon in the body?
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Which of the following processes does glucagon promote?
Which of the following processes does glucagon promote?
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In what organ does glucagon primarily exert its effects?
In what organ does glucagon primarily exert its effects?
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Study Notes
Glycogenolysis
- Breakdown of glycogen
- Occurs in starving state and exercising muscles
- Primarily takes place in the liver and muscles (cytosol)
- Key enzyme: Glycogen phosphorylase
- Glycogen phosphorylase removes glucose units from glycogen as glucose-1-phosphate
- Catalyzes the breakdown of α(1,4) glycosidic bonds
- Continues until four glucose units remain from a branch point (limit dextrin)
- Debranching enzyme removes glucose from the branch point (α(1,6) glycosidic linkage)
- Generates glucose-1-phosphate and free glucose (10:1 ratio)
Insulin
- Released due to high blood glucose levels (hyperglycemia)
- Produced by beta cells of the islets of Langerhans in the pancreas
- Lowers blood glucose by:
- Increasing glucose uptake by extrahepatic tissues for oxidation
- Promoting glycolysis and glycogenesis in liver and muscles
- Suppressing glycogenolysis in liver and muscles
- Suppressing gluconeogenesis in liver and kidneys
Glucagon
- Synthesized in response to low blood glucose levels (hypoglycemia)
- Produced by alpha cells of the islets of Langerhans in the pancreas
- Acts only in the liver to promote glycogenolysis
- Stimulates gluconeogenesis from lactate and amino acids
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Description
Explore the biochemical processes of glycogenolysis, including its role in energy metabolism during starvation and exercise. Additionally, learn about the regulatory functions of insulin and glucagon in maintaining blood glucose levels. This quiz covers key enzymes and physiological responses involved in glycogen metabolism.
