glucagon

(noun)

a hormone, produced by the pancreas, that opposes the action of insulin by stimulating the production of sugar

Related Terms

Examples of glucagon in the following topics:

  • Insulin Secretion and Regulation of Glucagon

    • Glucagon is a peptide hormone that works in conjunction with insulin to maintain a stable blood glucose level.
    • Glucagon and insulin are peptide hormones secreted by the pancreas that play a key role in maintaining a stable blood glucose level.
    • Liver cells have glucagon receptors and when glucagon binds to the liver cells they convert glycogen into individual glucose molecules and release them into the bloodstream—this process is known as glycogenolysis.
    • Insulin is produced by beta cells in the pancreas and acts to oppose the functions of glucagon.
    • Summarize the relationship between insulin secretion and glucagon regulation in blood glucose homeostasis

  • Postabsorptive State

    • This is accomplished via increased glucose levels from glucagon and decreased glucose levels from insulin.
    • Furthermore, during insulin and partial glucagon deficiency, and the exclusive partial deficiency of glucagon, the rate of glucose appearance increases to a point greater than the rate of glucose disappearance.
    • This rate increase seems to be even larger than during insulin and glucagon deficiency, as well as when glucagon is made exclusively deficient.
    • However, chronic insulin and glucagon deficiencies still remain victims of diabetes.
    • These findings do not distinguish the individual roles of insulin and of glucagon.

  • Interactions of Hormones at Target Cells

    • These cells control blood glucose concentration by producing the antagonistic hormones insulin and glucagon.
    • Alpha cells secrete glucagon.
    • Glucagon stimulates the liver to release glucose.
    • Glucagon also stimulates the production of ketone bodies from amino acids and fatty acids.
    • When blood glucose levels return to normal, glucagon secretion discontinues through negative feedback.

  • Hormonal Regulation of Metabolism

    • The levels of glucose in the blood are regulated by the hormones insulin and glucagon from the pancreas, and T3 and T4 from the thyroid.
    • Insulin and glucagon are the two hormones primarily responsible for maintaining homeostasis of blood glucose levels.
    • Glucagon also stimulates absorption of amino acids from the blood by the liver, which then converts them to glucose.
    • Rising blood glucose levels inhibit further glucagon release by the pancreas via a negative feedback mechanism.
    • In this way, insulin and glucagon work together to maintain homeostatic glucose levels .

  • Pancreas

    • As an endocrine gland, the pancreas produces several important hormones,such as insulin and glucagon, which are secreted into the bloodstream to regulate blood sugar levels, along with other activities throughout the body.
    • The pancreatic islets contain two primary cell types: alpha cells, which produce the hormone glucagon, and beta cells, which produce the hormone insulin.
    • As blood glucose levels decline, alpha cells release glucagon to raise the blood glucose levels by increasing rates of glycogen breakdown and glucose release by the liver.
    • The alpha and beta cells produce glucagon and insulin, respectively.

  • Types of Cells in the Pancreas

    • It is an endocrine gland that produces several important hormones, including insulin, glucagon, somatostatin, and pancreatic polypeptide.
    • Alpha cells that produce glucagon, and make up 15–20% of total islet cells.
    • Glucagon is a hormone that raises blood glucose levels by stimulating the liver to convert its glycogen into glucose.
    • The hormone glucagon activates alpha cells which then activate beta cells and delta cells.

  • Disease as Homeostatic Imbalance

    • Another hormone called glucagon performs the opposite function of insulin, causing cells to convert glycogen to glucose and stimulating new glucose production (gluconeogenesis) to raise blood sugar levels.
    • Negative feedback between insulin and glucagon levels controls blood sugar homeostasis.
    • With diabetes, blood glucose is increased by normal glucagon activity, but the lack of or resistance to insulin means that blood sugar levels are unable to return to normal.

  • Overview of Pancreatic Islets

    • Alpha cells that produce glucagon and make up 15–20% of total islet cells.
    • Glucagon is a hormone that raises blood glucose levels by stimulating the liver to convert its glycogen into glucose.
    • Insulin activates beta cells and inhibits alpha cells, while glucagon activates alpha cells, which activates beta cells and delta cells.

  • Histology of the Pancreas

    • It is both an endocrine gland producing several important hormones, including insulin, glucagon, somatostatin, and pancreatic polypeptide, as well as a digestive organ, secreting pancreatic juice containing digestive enzymes that assist the absorption of nutrients and the digestion in the small intestine.
    • They are relatively difficult to distinguish using standard staining techniques, but they can be classified by their secretion: α cells secrete glucagon (increase glucose in blood), β cells secrete insulin (decrease glucose in blood), delta cells secrete somatostatin (regulates/stops α and β cells), and PP cells or gamma cells, secrete pancreatic polypeptide.

  • Pancreas

    • As an endocrine gland, the pancreas produces several important hormones which include insulin, glucagon, somatostatin and pancreatic polypeptide.
    • They are relatively difficult to distinguish using standard staining techniques, but they can be classified by their secretion: α cells secrete glucagon (increase glucose in blood), β cells secrete insulin (decrease glucose in blood), delta cells secrete somatostatin (regulates/stops α and β cells), and PP cells or gamma cells, secrete pancreatic polypeptide.