Which hormone is secreted by the adrenal medulla and has various physiological effects including increasing heart rate?

The appropriate hormone secreted by the adrenal medulla that is known for its role in increasing heart rate is epinephrine, also commonly known as adrenaline. This hormone functions as a key component of the body's "fight or flight" response, preparing the body to respond to stress or danger. When released, epinephrine increases heart rate and cardiac output, enhances blood flow to muscles, and raises blood glucose levels, providing the body with an immediate energy source.

While both epinephrine and adrenaline refer to the same substance, the name adrenaline is more frequently used outside of technical contexts. Cortisol, on the other hand, is a glucocorticoid hormone that plays a significant role in stress responses but does not directly affect heart rate in the same way. Insulin is a hormone that regulates glucose levels in the blood and has a completely different role in metabolic processes. Understanding these distinctions helps clarify how epinephrine specifically aligns with the physiological effects mentioned in the question.