Flashcards in Diabetes: Physiology stuff Deck (12):
Why is the blood flow through the pancreas important?
Blood flows from the inside of the pancreas, where the insulin producing beta cells live, to the outer edges, where the glucugon-producing alpha cells live. Insulin can thus influence (decrease) glucugon release from the pancreas before it enters the bloodstream.
How do pancreatic beta cells sense glucose?
Glut-2 receptor/transporter, which increases its transport speed more after a meal than during a fast.
What role does ATP have on the K channel in the pancreatic beta cell?
it inhibits the outward flowing K channel. This leads to beta cell depolarization
Describe the biochemical pathways of the beta cell.
1. glucose enters via Glut-2 receptor
2. glucose converted to glucose-6-phosphate by glucokinase.
3. glucose-6-p enters the krebs cycle and generates ATP
4. ATP inhibits that ATP-dependent, outward-flowing K channel.
5. Cell is depolarized
6. deoplarization leads to opening of Ca2+ channels
7. Influx of Ca2+ increases phospholipase A2 and phoslpholipase C levels
8. This leads to increased IP3 and DAG
9. This leads to the release of Ca2+ from intracellular stores
10. Increase in calcium triggers the release of insulin-containing vesicles.
What is the physiological time course of insulin release?
quick spike immediately following a meal, and then another, slower rise about an 1 hr after the meal
What three organs/systems are most influenced by insulin levels?
liver, muscle, adipose tissue
Why are type II diabetics less likely to be acidotic than type I diabetics, at least during the early part of the disease?
acidosis caused by release of ketones from fatty acid oxidation. In the liver, ketone release is triggered largely by glucugon. Glucugon production is lower in type II diabetes because insulin is still produced by the beta cells, and this insulin inhibits glucugon production.
How do you diagnose diabetes?
-2 fasting blood glucose tests above 125
-1 blood glucose level above 200 2 hrs after the administration of 75 g glucose (glucose challenge)
-Hemoglobin A1C abover 6.5%
Any one of these characteristics is sufficient for diagnosis.
What is the basal bolus approach?
Give half daily insulin in a slow-acting formula to establish a base-line level of glucose
give the rest as boluses around meal times to limit hyperglycemia
What are 2 important innovations in insulin therapy?
1. Insulin pump, aka continuous subcutaneous insulin injections: this is a continuous drip, and it allows you to program the bolus doses
2. Continuous glucose monitoring: helps us create individualized plans.
Why is insulin secretion greater with oral glucose than with IV glucose?
Oral glucose stimulates the release of GLP1 and GIP peptides that increases the release of insulin when glucose levels are high