Insulin Preparations for Diabetes Mellitus Therapy Flashcards
What do alpha cells secrete?
Glucagon
What is the function of Glucagon?
Increase blood glucose
What do beta cells secrete?
Insulin and amylin
What is the function of Insulin?
Decrease blood glucose
What is the function of amylin?
Suppress glucagon release; delay gastric emptying and decrease food intake
What do delta cells secrete?
Somatostatin
What is the function of somatostatin?
Inhibit insulin & glucagon secretion
What do F cells secrete?
Pancreatic polypeptide
What is the function of pancreatic polypetide?
Unknown
What is C-peptide used as?
used as marker for insulin secretion (can help distinguish between different types of diabetes)
What is the main factor that controls the synthesis and secretion of insulin?
Blood glucose concentration
What are the nutrient stimulants of insulin synthesis and secretion?
Glucose, amino acids, and fatty acids
What are the nutrient inhibitors of insulin synthesis and secretion?
Chronic elevations in glucose and fatty acids
what are hormone stimulants of insulin synthesis and secretion?
Glucagon-like polypeptide (GLP-1) and Glucose-dependent insulinotropic polypeptide (GIP)
What are the hormone inhibitors of insulin synthesis and secretion?
Somatostatin
What are the neural stimulants of insulin synthesis and secretion?
Parasympathetic (Vagal) activation
What are the neural inhibitors of insulin synthesis and secretion?
Sympathetic (alpha-2 receptor) activation
What are then drugs stimulants of insulin synthesis and secretion?
Sulfonylureas, meglitinide, nateglinide
What are the drug inhibitors of insulin synthesis and secretion?
Diaxozide
What is the insulin release like from beta cells (in low concentration of glucose) ?
- Low glucose
- Low ATP
- The ATP-sensitive K+ channels open when low concentrations of ATP
- The K+ leaves the cell, and it reaches the resting membrane potential
- The Ca2+ channels stay closed, and no calcium enters the cell
- No exocytosis is triggered and the insulin remains in the vesicles
Where is GLUT 5 found?
Gut and kidney
What is the function of GLUT5?
Absorption of fructose
What is insulin?
Anabolic hormone –> required for normal growth and protein synthesis
When is insulin secreted?
In response to increased blood glucose levels
How does insulin lower blood glucose levels?
- Increase in GLUT 4 mediated glucose uptake & utilization in skeletal muscle and adipose tissue
- Inhibition of liver gluconeogenesis and glycogenolysis and prevention of glucose release from the liver into the blood
- Stimulation of glycogen production, protein synthesis and triglyceride formation in target organs
What are the effects of insulin on the liver? (7)
Increase glycolysis
Increase glycogenesis
Decrease gluconeogenesis
Decrease glycogenolysis
Increase lipogenesis
Decrease lipolysis
Decrease protein breakdown
What are the effects of insulin on the adipose tissues? (5)
Increase glucose uptake
Increase glycerol synthesis
Increase triglyceride synthesis
Increase fatty acid synthesis
Decrease lipolysis
What are the effects of insulin on the skeletal muscle? (5)
Increase glucose uptake
Increase glycolysis
Increase glycogenesis
Increase amino acid uptake
Increase protein synthesis
Where is insulin secreted from?
Beta cells of Langerhans
What is insulin synthesized from?
Two precursors (preproinsulin and proinsulin)
What is insulin stored as?
Hexamers in secretory vesicles
How does insulin circulate?
As a free monomer with a half-life of about 5 minutes
Where does the degredation of insulin occur?
In the liver (60%) by Thiol metalloproteinase
In the kidney (40%) in the renal tubulses
Why is exogenous insulin usually administered parenterally?
Usually given as an SC injection because insulin is a protein that is rapidly degraded ORALLY