Why do we perceive chili peppers as "hot" and peppermint as "cold"?

Question

 TRP channels normally act as temperature sensors in the body -- they are stimulus-gated ion channels, each specialized to open at various temperature thresholds. However, different TRP channels can also be gated by certain molecules such as capsaicin or menthol.

A.  It is a cultural convention to speak of chili peppers as hot and peppermint as cold.
B.  Capsaicin and menthol act as agonists of TRP channels normally activated by temperature changes.
C.  We are conditioned to think so because chili-containing foods are served hot, while mint-containing foods are served cold.
D.  Neurons sensitive to heat or capsaicin project to nearby regions of the brain, while neurons sensitive to cold or menthol project to other adjacent regions.
E.  Capsaicin transmits infrared energy, while menthol absorbs it.

Clarify Question
What is the key concept addressed by the question?
What type of thinking is required?

Gather Content
What do you already know about TRP channels? What other information is related to the question?

Choose Answer
Given what you now know, what information is most likely to produce the correct answer?

Reflect on Process
Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?

Answer 1

B.  Capsaicin and menthol act as agonists of TRP channels normally activated by temperature changes.


Clarify Question
What is the key concept addressed by the question?
        · Why is chili perceived as hot and mint as cold?
What type of thinking is required?
            o This is an analyze question because you have to break down the process of thermoreception and then explain why some chemical compounds elicit a sensation of temperature (either hot or cold).

Gather Content
What do you already know about TRP channels? What other information is related to the question?
        · You already know that TRP channels are found in nociceptors that respond to temperature changes. You also may recall that the first TRP receptor discovered responds to the chemical capsaicin, which is found in chili peppers, as well as to heat. Thus, when you eat spicy foods with capsaicin it provides a sensation of heat and pain.

Choose Answer
Given what you now know, what information is most likely to produce the correct answer?
        · Since TRP channels are activated by temperature changes, but capsaicin and menthol act as agonists of TRP channels, these molecules are perceived as hot and cold, respectively. Infrared energy or cultural conventions are not involved in the process.

Reflect on Process
Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?
        o Answering this question correctly depended not only on understanding that TRP channels monitor temperature changes, but also on your knowledge that TRP channels can be activated by compounds such as capsaicin and menthol. If you got an incorrect answer, did you think that the TRP channels responsive to different compounds go to different regions of the brain? Did you think that cultural conventions of what we consider hot and cold were involved?