The pancreas

The pancreas

  • has both exocrine and endocrine functions

  • majority of cells produce pancreatic juices

    • amylase

    • trypsinogen (inactive protease)

    • lipase

    • sodium hydrogen carbonate

  • endocrine cells produce glucagon and insulin which control blood glucose level

pancreatic function green is exocrine purple is endocrinemicroscopic view of pancreas

Islet of Langerhans = endocrine cells

  • looks like an island on an image

  • highly vascular

  • alpha cells produce glucagon

  • beta cells produce insulin

Acinus = circle of exocrine cells releasing into a duct

acinus

Blood glucose levels

  • normal blood glucose levels is 90mg/100cm³

  • if conc varies above or below then alpha and beta cells detect and release appropriate hormone

    • negative feedback

  • controlling blood glucose levels
release of insulin to lower blood glucose levels (in beta cells) (potassium ions are chemical gated calcium ions are voltage gated)inhibition of insulin to increase blood glucose levels (in beta cells)

Role of insulin

  • insulin binds to specific receptors on cell membrane of all cells but specifically liver and muscle cells

    • causes glucose channels to open so glucose can enter the cell

    • via cAMP

  • inulin stimulates:

    • respiration - so more glucose is respired

    • conversion of glucose into glycogen in liver and muscle cells

      • glycogenesis

    • conversion of glucose into fatty acids then fats which are stored in adipose tissues

  • role of insulin

  • above diagram simplified

Role of glucagon

  • glucagon binds to specific receptors in plasma membranes

  • activates enzymes that convert glycogen to glucose

    • glycogenolysis

  • stimulates conversion of amino acids to glucose

Key words

  • Glucose

    • simple sugar produced from carbohydrates

  • Glycogen

    • polysaccharide that is the main form of carbohydrate storage in animals

  • Glucagon

    • hormone that causes blood glucose levels to rise

  • Insulin

    • hormone that causes blood glucose levels to fall

  • Glycogenolysis

    • conversion of glycogen to glucose

  • Glycogenesis

    • conversion of glucose to glycogen

  • Gluconeogenesis

    • production of glucose from amino acids (pyruvate and lactate)