Thermoreceptor

A thermoreceptor is a non-specialised sense receptor, or more accurately the receptive portion of a sensory neuron, that codes absolute and relative changes in temperature, primarily within the innocuous range.

Some cold receptors also respond with a brief action potential discharge to high temperatures, i.e. typically above 45 °C, and this is known as a paradoxical response to heat [citation needed].

In humans, along the axons of Lissauer's tract temperature or pressure sensations enter the spinal cord.

The Lissauer's tract will synapse on first-order neurons in grey matter of the dorsal horn, one or two vertebral levels up.

In the cornea cold receptors are thought to respond with an increase in firing rate to cooling produced by evaporation of lacrimal fluid 'tears' and thereby to elicit a blink reflex [citation needed].

Studies performed on mice determined that the presence of both these receptors allows for a gradient of temperature sensing.

Mice lacking the TRPV1 receptor were still capable of determining areas significantly colder than on a heated platform.

[5] This area of research has recently received considerable attention with the identification and cloning of the Transient Receptor Potential (TRP) family of proteins.

Another molecular component of cold transduction is the temperature dependence of so-called leak channels which pass an outward current carried by potassium ions.

It has been suggested that it is the constellation of various thermally sensitive proteins together in a neuron that gives rise to a cold receptor.