What role does adrenaline play in the body?

Adrenaline, also known as epinephrine, is a hormone released by the adrenal glands, particularly during times of stress or threat. Its primary role is to prepare the body for a rapid response, often referred to as the "fight or flight" response. When adrenaline is released into the bloodstream, it has several physiological effects that enhance physical performance and readiness.

One of the most significant effects of adrenaline is its action on the muscles. It increases the availability of energy substrates, such as glucose, and improves blood flow to the muscles by dilating blood vessels. This prepares the muscles for exertion, allowing for quicker reactions and stronger physical performance in response to stress or danger. In high-stress situations, this immediate readiness is critical for survival.

While the other options address different physiological roles, they do not align with the well-established functions of adrenaline. Lowering blood pressure, conserving energy, and inducing sleepiness and relaxation aren't representative of the adrenaline response, which seeks to mobilize energy and enhance alertness rather than promote comfort or relaxation.