Final answer:
When blood glucose concentration is high, insulin triggers a cascade of events that cause more GLUT-4 transporters to be inserted into the cell membrane, increasing the number of glucose transporters available for glucose uptake into the cell.
Step-by-step explanation:
When blood glucose concentration is high, there is a higher presence of insulin in the bloodstream. Insulin triggers a cascade of events that cause GLUT-4 (glucose transporter) vesicles to fuse with the plasma membrane. This allows more GLUT-4 transporters to be inserted into the cell membrane, increasing the number of glucose transporters available for glucose uptake into the cell. As a result, cells will have more GLUT-4 working in the membrane when blood glucose concentration is high.