Question

Patient had sunburn and now takes a bath with 40-degree water and feels pain.

• A. Thermal receptor: hyperalgesia
• B. Innocuous thermal receptor: allodynia
• C. Thermal receptor: allodynia
• D. Innocuous thermal receptor: hyperalgesia

Hint:

Allodynia occurs when typically harmless stimuli, such as warm water after a sunburn, trigger pain due to sensitized thermal receptors.

Answer 1

The Correct Option is B

The scenario involves a patient who experiences pain when bathing in 40-degree water after having a sunburn. This condition relates to how skin receptors respond to different stimuli due to altered skin sensitivity.

Analysis:

• Sunburn Effect: Sunburn damages the skin, which can lead to heightened sensitivity and altered pain perception.
• Receptors & Pain Response: Typically, nerve endings in the skin detect temperature changes. Thermal nociceptors detect painful heat, while innocuous thermal receptors detect nonpainful temperature changes.
• Innocuous vs. Noxious Stimuli: In normal conditions, 40-degree water is nonpainful (innocuous), not expected to trigger pain response. However, in the context of sunburn, this mild heat might elicit pain.
• Allodynia: When nonpainful stimuli become painful, it is termed ‘allodynia’. This occurs due to changes in pain threshold post-damage.

Conclusion: The pain experienced is due to an altered response from innocuous thermal receptors, classifying this sensation as allodynia.

Correct Answer: Innocuous thermal receptor: allodynia