Practice question

Sweating is a negative-feedback response that helps keep core temperature near its regulated set range. Thermoreceptors in the skin and body core signal the hypothalamus when temperature rises. The hypothalamus activates sweat glands and promotes cutaneous vasodilation. Evaporation of water from the skin absorbs latent heat, cooling the body; as temperature returns toward the set range, the stimulus and response diminish. This feedback structure—deviation, detection, corrective response, and reduction of deviation—is characteristic of homeostasis. Sweating works best when air is dry and moving; high humidity reduces evaporation and therefore cooling. It also costs water and salts, requiring fluid balance mechanisms. Fever is different because pyrogens raise the hypothalamic set point; chills may occur even while measured temperature is elevated, so fever is a regulated shift rather than an example of cooling back to the original set point. Eye-colour change is not a standard human homeostatic response, and behavioural mimicry concerns resemblance to another organism. Homeostasis does not mean an absolutely constant internal state; it means dynamic regulation within limits through coordinated physiological feedback.