The physiological basis of the fight-or-flight response involves the activation of the autonomic nervous system during stressful situations. When faced with a threat, the body releases hormones such as adrenaline and cortisol. These hormones prepare the body for immediate action, increasing heart rate, blood pressure, and energy supplies. The sympathetic nervous system (SNS) is primarily responsible for these changes, promoting heightened alertness and physical readiness. This response is vital for survival, allowing individuals to either confront challenges or escape them effectively.