Which condition triggers insulin release?

Which condition triggers insulin release?

• A. Low blood glucose
• B. High blood glucose
• C. Low oxygen
• D. Low pH

Answer: (B)

When blood glucose rises, pancreatic beta cells release insulin. Glucose enters these cells through GLUT2 transporters, is metabolized to raise ATP, and this increase closes ATP-sensitive potassium channels. That closes the K+ leak, depolarizes the cell membrane, opens voltage-gated calcium channels, and the influx of calcium triggers exocytosis of insulin-containing granules. Insulin then promotes glucose uptake into liver, muscle, and fat tissues and stimulates storage of glucose as glycogen and fat, lowering blood glucose back toward normal levels. Low blood glucose wouldn't trigger insulin; it instead promotes glucagon release to raise glucose. Low oxygen or low pH don't directly trigger insulin release.

When blood glucose rises, pancreatic beta cells release insulin. Glucose enters these cells through GLUT2 transporters, is metabolized to raise ATP, and this increase closes ATP-sensitive potassium channels. That closes the K+ leak, depolarizes the cell membrane, opens voltage-gated calcium channels, and the influx of calcium triggers exocytosis of insulin-containing granules. Insulin then promotes glucose uptake into liver, muscle, and fat tissues and stimulates storage of glucose as glycogen and fat, lowering blood glucose back toward normal levels.

Low blood glucose wouldn't trigger insulin; it instead promotes glucagon release to raise glucose. Low oxygen or low pH don't directly trigger insulin release.