metabolism and insulin Flashcards
glucagon: explain glucagon synthesis, storage and secretion; list the physiological actions of glucagon, explain the mechanism of action and explain factors regulating release of glucagon
what cell in the islets of langerhans produce glucagon
a-cells
how does glucose enter a-cells
via GLUT-2
what acts as the glucose sensor in a-cells
glucokinase (hexokinase IV)
how does glucagon increase blood glucose
increases hepatic glycogenolysis, amino acid transport to liver, gluconeogenesis and lipolysis
what causes a-cells to function: increase glucagon release
certain amino acids, certain gastrointestinal hormones, parasympathetic activity and sympathetic activity
what causes a-cells to function: decrease glucagon release
insulin, somatostatin
what is glucagon like peptide-1 (GLP-1) and what does it do
gut hormone secreted in response to nutrients; stimulates insulin and suppresses glucagon and increases satiety (feeling of being “full”)
what is glucagon like peptide-1 (GLP-1) a transcription product of
proglucagon gene
why does glucagon like peptide-1 (GLP-1) have a short half life
rapid degradation from dipeptidyl peptidase-4
how is glucagon released from a-cell
glucokinase activated → glucose-6-phosphate and ATP formed → ATP closes voltage-gated K+ channel → voltage-gated Ca2+ channel opens → Ca2+ influx → vesicles containing glucagon fuse with plasma membrane → release of glucagon by exocytosis
