Which hormone is responsible for facilitating the uptake of sugar into cells from the bloodstream?

Insulin is a hormone produced by the pancreas that plays a crucial role in regulating blood sugar levels. Its primary function is to facilitate the uptake of glucose, a form of sugar, into the body's cells from the bloodstream. When you consume food, particularly carbohydrates, your blood sugar levels rise. In response, the pancreas releases insulin, which binds to insulin receptors on cell surfaces, prompting the cells to absorb glucose. This process helps lower blood sugar levels and provides cells with the energy they need to function.

In contrast, glucagon functions oppositely by increasing blood sugar levels when they are too low by promoting the release of glucose from stored glycogen in the liver. Adrenaline is involved in the "fight or flight" response and raises blood sugar levels to provide immediate energy. Cortisol is a stress hormone that can affect metabolism and increase blood sugar levels during stress. Therefore, while these other hormones play critical roles in regulating energy and metabolism, insulin is specifically the one that directly facilitates the uptake of sugar into cells from the bloodstream.