What role does cortisol play in the body's response to stress?

Cortisol plays a crucial role in the body's response to stress primarily by increasing blood glucose availability. During a stressful situation, the body requires additional energy to deal with the threat or challenge it faces. Cortisol facilitates this by promoting gluconeogenesis, which is the process of producing glucose from non-carbohydrate sources in the liver. This action raises blood sugar levels, making glucose readily available for use as an immediate energy source by vital organs and muscles, which is essential during times of stress.

The other options, while they may touch upon various metabolic effects of cortisol, do not reflect its primary function during stress. For instance, although cortisol can influence the metabolism of fats and proteins, its main role in acute stress reactions is aimed at ensuring that adequate energy supplies are available. Thus, the correct understanding of cortisol's function in this context is how it elevates blood glucose levels to support the body's immediate energy needs during stress.