Which hormone is the primary stress hormone that increases heart rate and blood pressure?

• A. Epinephrine
• B. Cortisol
• C. Insulin
• D. Aldosterone

Answer: (A)

Epinephrine is the fast-acting mediator of the stress response. When stress hits, the sympathetic nervous system triggers its release from the adrenal medulla. In the heart, epinephrine binds beta-1 receptors, raising heart rate and contractility, which increases cardiac output. In many blood vessels, it binds alpha-1 receptors to induce vasoconstriction, raising systemic vascular resistance and blood pressure. It also boosts energy availability by promoting glycogenolysis and lipolysis to supply quick fuel for the body’s immediate actions.

Cortisol, while part of the stress response, acts more slowly and mainly supports sustained glucose production and various metabolic adjustments over time, rather than acutely increasing heart rate. Insulin lowers blood glucose and is not a principal mediator of the stress-induced cardiovascular surge. Aldosterone primarily regulates fluid balance and long-term blood pressure via sodium and water retention, not the rapid heart rate rise seen in acute stress.