tailieunhanh - Ebook Marks' essentials of medical biochemistry a clinical approach (2nd edition): Part 2

(BQ) Part 1 book "Marks' essentials of medical biochemistry a clinical approach" presents the following contents: Carbohydrate metabolism, lipid metabolism, nitrogen metabolism. Invite you to consult. | SECTION FIVE Carbohydrate Metabolism Basic Concepts in the Regulation of Fuel Metabolism by Insulin Glucagon and 21 Other Hormones CHAPTER OUTLINE I. METABOLIC HOMEOSTASIS II. MAJOR HORMONES OF METABOLIC HOMEOSTASIS III. SYNTHESIS AND RELEASE OF INSULIN AND GLUCAGON A. Endocrine pancreas B. Synthesis and secretion of insulin C. Stimulation and inhibition of insulin release D. Synthesis and secretion of glucagon KEY POINTS IV. MECHANISMS OF HORMONE ACTION A. Signal transduction by hormones that bind to plasma membrane receptors 1. Signal transduction by insulin 2. Signal transduction by glucagon B. Signal transduction by cortisol and other hormones that interact with intracellular receptors C. Signal transduction by epinephrine and norepinephrine Insulin and glucagon are the two major hormones that regulate fuel mobilization and storage. Insulin and glucagon maintain blood glucose levels near 80 to 100 mg dL despite varying carbohydrate intake during the day. Glucose homeostasis is the maintenance of constant blood glucose levels. If dietary intake of all fuels is in excess of immediate need it is stored as either glycogen or fat. Appropriately stored fuels are mobilized when demand requires. Insulin is released in response to carbohydrate ingestion and promotes glucose utilization as a fuel and glucose storage as fat and glycogen. Glucagon is decreased in response to a carbohydrate meal and elevated during fasting. Glucagon promotes glucose production via glycogenolysis glycogen degradation and gluconeogenesis glucose synthesis from amino acids and other noncarbohydrate precursors . Increased levels of glucagon relative to insulin also stimulate the release of fatty acids from adipose tissue. Insulin secretion is regulated principally by blood glucose levels. Glucagon release is regulated principally through suppression by glucose and by insulin. Glucagon acts by binding to a receptor on the cell surface which stimulates the synthesis of the intracellular second .