What physiological response occurs when a person is in a state of intense fear or stress?

When a person experiences intense fear or stress, one of the physiological responses is the dilation of pupils, often referred to as mydriasis. This response is part of the body's fight-or-flight mechanism, which prepares an individual to respond to perceived threats.

During moments of stress or fear, the body releases adrenaline, which activates various systems to enhance survival. Dilation of the pupils allows more light to enter the eyes, improving vision and enabling the individual to better assess their environment for potential dangers. This physiological change enhances visual acuity, allowing for greater awareness of surrounding stimuli, which can be crucial in threatening situations.

In contrast, decreased heart rate and increased digestive functions are not typically associated with a stress response; rather, they are more aligned with relaxation or calm states. Additionally, decreased alertness contradicts the intended purpose of the fight-or-flight response, which is to heighten awareness and readiness to act. Thus, pupil dilation serves an essential role in the body's overall reaction to fear and stress.