Pathophysiology of Carbohydrate Metabolism Flashcards
Glucose enters pancreatic beta cells via GLUT-2 receptors. How is the release of glucose then stimulated?
Glucose undergoes glycolysis in beta cells, producing ATP. Increased ATP closes potassium channels and depolarizes the cell. Calcium channels open and calcium influx-induced insulin exocytosis.
This type of hypoglycemia occurs after eating a meal and is often due to rapid movement of food through shortened bowels.
Postprandial (Reactive) Hypoglycemia
This molecule in produced from the cleavage of proinsulin and directly reflects insulin release.
C-peptide
Low c-peptide with high insulin indicates exogenous insulin injection
This is the best maker of endogenous insulin secretion.
C-peptide
True/False. Nearly half of all secreted insulin is filtered by the liver before entering circulation.
True - only 50% of secreted insulin enters circulation.
Somatostatin (increases/decreases) insulin secretion and (increases/decreases) glucagon secretion.
Somatostatin inhibits both insulin and glucagon secretion
These counter-regulatory hormones act similarly to glucagon to generate fuel for the body.
Catecholamines, cortisol, growth hormone, thyroid hormone
What is the effect of epinephrine on skeletal muscle?
Epinephrine promotes glycogenolysis in skeletal muscle. Since muscle lacks glucose-6-phosphatase, lactate is produced
These amino acids are coupled with sodium transporters that can induce beta-cell depolarization and insulin release.
Glycine, alanine, arginine
A patient presents with symptoms of hypoglycemia. Blood test reveals high glucose levels. The patient fasts, but high insulin levels persist. What is the likely diagnosis?
Insulinoma - neuroendocrine tumor that secretes insulin
This enzymatic pathway mediates the mitogenic functions of insulin.
MAP Kinase pathway
Diagnosis of hypoglycemia requires fulfilling Whipple’s triad. What is Whipple’s triad?
Symptoms of hypoglycemia, low serum glucose, resolution of symptoms with supplemental glucose
Diabetes is associated with an increased risk of cardiovascular complications. What is one reason for this?
Insulin is a vasodilator that increases NO synthesis. Diabetic patients lose this function due to low insulin, leading to increased vasoconstriction
What medical condition contributes most to the pathogenesis of metabolic syndrome?
Insulin resistance
True/False. Carbohydrates provide more energy than fatty acids.
False. Carbs and proteins provide 4kcal. Fats provide 9kcals.
True/False. Insulin can cause hyperkalemia.
False. Insulin induces the Na/K ATPase and moves K+ into cells. Insulin is used in the treatment of life-threatening hyperkalemia
What is the relationship between free fatty acids and insulin?
Insulin inhibits lipolysis to decrease free fatty acids. Excess free fatty acids contribute to the development of insulin resistance
This is the functional endocrine part of the pancreas.
Islets of Langerhans
What is the effect of sulfonylurea on blood glucose?
Sulfonylurea lowers blood glucose and may cause hypoglycemia
This enzymatic pathway mediates the metabolic actions of insulin.
PI3K Pathway
During periods of fasting, what is the progression of glucose use?
Plasma glucose –> glycogenolysis –> gluconeogenesis
Liver glycogenolysis can only provide glucose for approx. 16 hours
What are the first symptoms of hypoglycemia?
Autonomic symptoms such as sweating, anxiety, palpitations, and dizziness. Neurologic symptoms follow due to continued low glucose
This hormone functions to regulate energy balance and body weight. Resistance to this hormone is associated with obesity.
Leptin - produced by adipose tissue to suppress appetite
What is the function of adiponectin?
Adiponectin inhibits gluconeogenesis and promotes beta-oxidation of fatty acids serving to decrease plasma glucose levels
