W27-L2: Post-Prandial glucose metabolism Flashcards
What are the 4 cell types in the islets of langerhans and what do they secrete?
β-cells: insulin and amylin
δ-cells: somatostatin
α-cells: glucagon
φ-cells: pancreatic polypeptide
What are the roles of prohormone convertases?
PC 2 cleaves pre-pro to pro, PC 1 cleaves pro to insulin
Which chain of insulin is not highly conversed?
Other chains are conserved across animals but C peptide varies greatly and is allowed to mutate
What is insulin packaged with in secretory granules?
Endopeptidase enzymes
What are the phases of insulin secretion?
1st phase is a sharp rise that lasts for 2-5 minutes
2nd phase is if glucose is still high, prolonged secretion that lasts for duration of stimulus
Where are GLUT 2 and glucokinase expressed?
Pancreas and Liver
What is special about GLUT 2 and glucokinase?
High Km, So GLUT 2 is not saturated quickly, proportional uptake to blood levels
How does amino acids stimulate insulin secretion?
Increased ATP via TCA cycle then closes K+ channels and lets Ca2+ (like glucose)
How does fatty acids stimulate insulin secretion?
Via increasing Malonyl CoA which inhibits CPT-I
When is more insulin secreted, after oral or IV administration? Why?
Oral, glucose in the gut triggers hormones to induce insulin secretion
What are Incretins?
gut-derived hormones secreted in response to nutrients eg. glucose, fatty acids, amino acids
What are two examples of incretins?
GLP-1 and GIP
What is the role of Glucagon like peptide 1 (GLP-1)
stimulates proinsulin biosynthesis and release as well (but only if glucose is high)
promotes ß cell growth and function
What isn’t GLP-1 used for T2D?
Short half life
What are the therapeutic agents related to GLP-1?
Agonists (analogues of GLP-1) and DPP-4 inhibitors (inhibit enzyme which break it down)
