Final answer:
Insulin is the hormone released by the pancreas that helps cells take in glucose or store it as glycogen when blood sugar levels are high. It is produced by the beta cells in the pancreatic islets. Glucagon, on the other hand, is released to raise blood sugar levels when they are low.
Step-by-step explanation:
The hormone released by the pancreas that helps usher glucose into cells or store it as glycogen when blood sugar levels are high is insulin. The pancreatic islets, or the islets of Langerhans, contain beta cells which produce insulin. When blood glucose levels rise, for instance, after eating, these beta cells secrete insulin into the bloodstream. Insulin then signals cells to take up excess glucose from the blood for ATP production or to convert it to glycogen for storage in the liver and muscles. The action of insulin effectively lowers the blood glucose levels to a normal range.
In contrast, when blood glucose levels fall, alpha cells of the pancreas secrete glucagon, which has the opposite effect – stimulating the conversion of glycogen back into glucose in the liver and releasing it into the bloodstream to raise blood glucose levels to a normal range again.