Problem 10 - Biology: The Dynamic Science

Question

In the human response to temperature or pain: a. all three transient receptor potential (TRP) gated \(\mathrm{Ca}^{2+}\) channels act as pain receptors. b. cold receptors are activated between \(27^{\circ} \mathrm{C}\) and \(37^{\circ} \mathrm{C}\) c. pain receptors decrease the rate at which they send out action potentials if the pain is constant. d. nociceptors, activated by capsaicin in the mouth and nose, can sense pain. e. the CNS releases glutamate or substance \(P\) to dull the pain sensation.

Step-by-Step Solution

Answer

Statements a, b and d are true, while statements c and e are false.

Step 1: Check Statement a

The statement a refers to transient receptor potential (TRP) gated \(\mathrm{Ca}^{2+}\) channels acting as pain receptors. This is indeed true, as TRP channels have been identified as mediators of thermal, chemical, and mechanical pain sensations.

Step 2: Check Statement b

Statement b suggests cold receptors are activated between \(27^{\circ} \mathrm{C}\) and \(37^{\circ} \mathrm{C}\). This is true as thermal receptors located in the skin, muscle, and other tissues respond to changes within this range of temperature.

Step 3: Check Statement c

Statement c suggests that pain receptors decrease the rate at which they send out action potentials if the pain is constant. This is not entirely accurate. A constant pain might not result in the rate of action potentials decreasing but can result in an exaggerated response, a condition referred as hyperalgesia.

Step 4: Check Statement d

Statement d mentions nociceptors and their activation by capsaicin. This statement is true: nociceptors are sensory neurons that respond to potentially damaging stimuli by sending signals to the spinal cord and brain. Capsaicin, the compound that gives chilies their burn, can indeed activate such receptors in the mouth and nose.

Step 5: Check Statement e

Statement e suggests that the CNS releases glutamate or substance \(P\) to dull the pain sensation. This is not true. Glutamate and substance \(P\) are released as a response to pain and they enhance, not dull, the pain sensation by transmitting the pain signals to the brain.