Introduction

Have you ever felt a flash of anxiety or hesitation just before hearing your exam results, or noticed goosebumps rising on your skin during a sudden, unexpected moment? These everyday reactions are not just imagined — they are real, rapid biochemical changes taking place inside the body, and the endocrine system is what produces them. In both cases the hormone responsible is adrenalin (also called epinephrine), often nicknamed the 'flight, fright and fight' hormone because it prepares the body to respond instantly to a stressful or startling situation.