33 Physiology of Insulin Secretion Flashcards
How many islets are in the pancreas?
3 million islets
Total weight of endocrine pancreas
1 g
Most abundant cell type in pancreatic islets
Beta cells (60%)
Glucose transporter in beta cells
GLUT2
First rate limiting step in the glycolytic pathway
Phosphorylation of glucose to glucose-6-phosphate
Enzyme that mediates phosphorylation of glucose
Glucokinase
Effect of sympathetic stimulation to insulin and glucagon secretion
Inhibits insulin secretion
Potentiates glucagon secretion
(Alpha 2 mediated NE release)
Effect of parasympathetic stimulation to insulin and glucagon secretion
Enhances insulin and glucagon release
(M3 mediated)
Most beta-cell neogenesis occurs during this period
Preterm
Most beta cell neogenesis occurs during:
Preterm
Full complement of beta cells is established within how many years of life
5 years
Average lifetime of beta cells
25 years
Estimated pancreatic insulin content
200-250 units
Number of secretory granules within beta cell cytoplasm
5000-8000
Insulin granule half life
<5 days
Proportion of renal C-peptide uptake that is excreted intact
15%
Fraction of portal insulin that is removed by the liver in its first pass
65% (50-70%)
Overall contribution of the liver to insulin clearance (first pass plus recirculation)
80%
Among antidiabetic agents, this drug class is known to reduce insulin clearance
Sulphonylurea
Contribution of first phase insulin secretion in suprabasal secretion during 2 hour OGTT
10% or ~3 nmol/m2
Pulse intervals of insulin secretion
5-14 mins
Slower ultradian cycles of insulin secretion
80-180 mins
First phase insulin secretion lasts for how long
5-8 mins
Phenomenon that describes that plasma glucose and insulin secretory responses are attenuated during the second, as compared to with the first meal
Staub-Traugott effect
