Which of the following is a key symptom of heat stress?

A key symptom of heat stress is the presence of dry membranes. Normally, during heat stress, the body loses fluids through sweating in an effort to cool down. If the body is unable to properly cool itself due to excessive heat exposure or dehydration, it can lead to a reduction in sweating, resulting in dry mucous membranes. This condition is a significant indicator of dehydration and can accompany other symptoms of heat-related illnesses.

Understanding why dry membranes signify heat stress involves recognizing the physiological response of the body to high temperatures. When the body overheats, it attempts to cool itself primarily through perspiration. If dehydration occurs, the production of sweat diminishes, leading to dry membranes in the mouth and nasal passages. Additionally, this symptom can alert health professionals to the severity of the situation, indicating that immediate intervention may be necessary to prevent further complications, such as heat exhaustion or heat stroke.

In examining the other options, slow pulse and dilated eyes are not commonly associated with heat stress as primary symptoms, while moist membranes would typically indicate adequate hydration and functioning cooling mechanisms through sweating. Therefore, the presence of dry membranes effectively points toward heat stress complications.