Blood glucose regulation Knowledge-Based Download PDF

Questions

1. 1.

   In pancreatic beta cells, which cellular event directly causes the membrane depolarization required to open voltage-gated calcium channels and stimulate insulin secretion?

   • A) Opening of ligand-gated sodium channels upon extracellular glucose binding to membrane receptors
   • B) Influx of chloride ions through transmitter-activated channels causing hyperpolarization
   • C) Closure of ATP-sensitive potassium channels following an increase in the intracellular ATP-to-ADP ratio
   • D) Direct stimulation of voltage sensors by glucose-6-phosphate accumulating in the cytoplasm
2. 2.

   Which hormone is secreted by the delta (δ) cells of the pancreatic islets to exert a paracrine inhibitory effect on the secretion of both insulin and glucagon?

   • A) Pancreatic polypeptide
   • B) Cholecystokinin
   • C) Somatostatin
   • D) Glucagon-like peptide-1
3. 3.

   Why does glucagon stimulate the release of free glucose into the bloodstream from hepatocytes but not from skeletal muscle cells?

   • A) Hepatocytes express glucagon receptors and glucose-6-phosphatase, whereas skeletal muscle cells lack these components.
   • B) Skeletal muscle cells store glucose as starch rather than glycogen, preventing enzymatic breakdown into free glucose.
   • C) Hepatocytes utilize insulin-dependent GLUT4 transporters to actively export glucose into the circulation during fasting.
   • D) Skeletal muscle cells rapidly degrade circulating glucagon via specialized membrane enzymes before receptor binding can occur.
4. 4.

   Following the digestion and absorption of a carbohydrate-rich meal, which cellular response is directly triggered by the primary regulatory hormone released from pancreatic beta cells to lower elevated blood glucose concentration?

   • A) Accelerated breakdown of stored glycogen into free glucose within hepatocytes
   • B) Translocation of GLUT4 storage vesicles to the plasma membrane in skeletal muscle cells and adipocytes
   • C) Upregulation of hepatic gluconeogenesis to synthesize glucose from non-carbohydrate precursors
   • D) Increased secretion of glucagon into circulation to stimulate fatty acid mobilization
5. 5.

   During prolonged fasting, which physiological mechanism is activated to return declining blood glucose concentration to its homeostatic set point?

   • A) Pancreatic beta cells secrete insulin to enhance cellular glucose uptake in adipocytes.
   • B) The adrenal medulla secretes aldosterone to stimulate glucose reabsorption in the distal tubules.
   • C) Skeletal muscle fibers hydrolyze intracellular glycogen and release free glucose into the systemic circulation.
   • D) Pancreatic alpha cells secrete glucagon, which stimulates glycogenolysis and gluconeogenesis in hepatocytes.