thermoreceptors

Thermoreceptors are sensory receptors that detect changes in temperature and provide information for both temperature sensation and the regulation of body temperature.

Peripheral thermoreceptors, located mainly in the skin, include cold receptors activated by cooling and warm receptors activated by warming. Central thermoreceptors in the hypothalamus and other brain regions monitor core temperature and help regulate autonomic responses.

Most thermoreceptors are free nerve endings of sensory neurons. Cold receptors typically transmit via A-delta fibers; warm receptors via C fibers, with different adaptation rates and thresholds.

Transduction involves temperature-sensitive ion channels, especially members of the transient receptor potential (TRP) family. TRPM8 responds to cool temperatures and menthol; TRPV1 responds to heat and capsaicin; other TRP channels contribute to warmth and noxious heat.

Information is relayed to the spinal cord and ascends to the thalamus and somatosensory cortex for conscious perception. A parallel pathway conveys signals to the hypothalamus to regulate vasomotor tone, sweating, shivering, and metabolic responses.

Clinical relevance: Thermoreception can be altered by aging, diabetes, or neuropathies. Fever results from hypothalamic set-point elevation during infection; impaired thermoreception increases risk of injury from extreme temperatures.