Insulin secretion+ intermediary metabolism Flashcards
Hormones that increase blood glucose levels
Glucagon
Catecholamines
Somatotrophin
Cortisol
Differences between type 1 and type 2 diabetes
1: insulin required to prevent ketoacidosis
2: more common, related to hypertension, dyslipidaemia
Other type of diabetes
MODY: Maturity Onset Diabetes of the young
When does hypoglycaemia occur?
Imbalance between diet, exercise, insulin
CNS relies on what energy source?
Importance?
Glucose
Hypoglycaemia= brain function impaired
Severe= unconsciousness, coma, death
Islets of Langerhans
Types of cells
Adaptations of islets?
α cells- glucagon= increase blood glucose
β cells
δ cells- somatostatin= inhibits effect of glucagon+ insulin
Gap junctions- allow small molecules to pass directly from cell to cell
Tight junctions- small intercellular spaces
β cells Stimulated by? Inhibited by? Produces? Mechanism? Effects?
Increased blood glucose, certain amino acids, certain gastrointestinal hormones, glucagon from α cells, β cell receptors (parasympathetic activity),
Somatostatin from δ cells , α cell receptors (sympathetic activity)
Insulin:
Glucose binds to GLUT-2 receptor+ becomes Glucose-6 phosphate through glucokinase enzyme
Metabolic reactions of glucose= produce ATP
ATP sensitive K+ channel is blocked= Ca2+ can enter through voltage dependent Ca2+ channe
Ca2+ causes release of stored insulin+ production of more insulin
Decreased lipolysis Decreased lipogenesis Decreased ketogenesis Increased amino acid transport Increased protein synthesis Decreased proteolysis Increased glycogenesis Increased glycolysis Increased glucose transport into cells via GLUT-4 Leads to decreased blood glucose Increase glucose muscle uptake Stimulates growth+ development
α cells Stimulated by? Inhibited by? Produces? Effects
Decreased blood glucose, sympathetic activity, parasympathetic activity, certain amino acids, certain GI hormones
Somatostatin from δ cells, insulin from β cells
Glucagon
Increased amino acid transport into liver= increased gluconeogenesis
Increased lipolysis= increased glucogenogensis
Increased hepatic glycogenolysis
Leads to increased blood glucose
Glucokinase (hexokinase IV)
Involved in rate limiting step during production of insulin from β cells
Insulin precursor
Proinsulin- made of insulin+ C-peptide
Oral intake of glucose vs IV infused glucose
e.g?
Oral= increased plasma glucose than in IV
Oral= food in GI tract stimulates incretins= increase insulin secretion more than just IV
E.g. GLP-1= gut hormone, transcribed from pro-glucagon gene, stimulates insulin+ suppresses glucagon, increases satiety, short half-life
Insulin receptor
2 extracullar α subunits bind to insulin, cause 2 transmembrane β sub-units to allow phosphorylation of cell protein substrates using tyrosine kinase domains
