Blood glucose regulation Knowledge-Based Practice

Questions

1. 1.

   Which molecular factor explains why glycogen stored in human skeletal muscle cannot be directly released as free glucose into the bloodstream to correct hypoglycemia?

   • A) Skeletal muscle fibers lack glycogen phosphorylase to break down stored glycogen into smaller sugar units.
   • B) Skeletal muscle fibers lack hexokinase to trap incoming glucose molecules within the sarcoplasm.
   • C) Skeletal muscle fibers lack glucose transporter 4 (GLUT4) proteins needed to facilitate outward diffusion into the bloodstream.
   • D) Skeletal muscle fibers lack glucose-6-phosphatase to convert glucose-6-phosphate into free glucose that can enter the bloodstream.
2. 2.

   Which metabolic pathway is stimulated by glucagon in hepatocytes to synthesize glucose from non-carbohydrate precursors such as glycerol and amino acids?

   • A) Glycogenolysis
   • B) Glycogenesis
   • C) Gluconeogenesis
   • D) Glycolysis
3. 3.

   Which of the following correctly pairs a pancreatic islet endocrine cell type with the hormone it secretes and that hormone's primary physiological action?

   • A) Pancreatic beta cells secrete glucagon to promote lipid accumulation in adipose tissue.
   • B) Pancreatic alpha cells secrete glucagon to stimulate glycogenolysis and gluconeogenesis in the liver.
   • C) Pancreatic alpha cells secrete insulin to suppress glycogen synthesis in skeletal muscle tissue.
   • D) Pancreatic beta cells secrete somatostatin to facilitate glucose entry through membrane transport proteins.
4. 4.

   Which cellular event is directly stimulated by insulin to decrease elevated blood glucose concentrations following a meal?

   • A) Hydrolysis of glycogen stores into glucose-6-phosphate in hepatocytes
   • B) Stimulation of hepatic gluconeogenesis from non-carbohydrate precursors
   • C) Increased secretion of glucagon by pancreatic alpha cells
   • D) Translocation of GLUT4 glucose transporter proteins to the plasma membrane
5. 5.

   Which of the following physiological responses occurs in a healthy human when blood glucose concentrations drop below normal fasting levels?

   • A) Beta cells of the pancreas secrete insulin to stimulate cellular glucose uptake.
   • B) Liver cells increase the conversion of circulating glucose into stored glycogen.
   • C) Adipose tissue accelerates the synthesis and storage of triglycerides from glucose.
   • D) Alpha cells of the pancreas secrete glucagon to promote glycogenolysis in the liver.

Answers and step-by-step solutions appear after you finish the test.