Electrophysical Agents: Why Rubbing a Bump Eases the Pain
Heat, cold, sound, light and electricity in rehabilitation: how they act on nerves and tissues, what the evidence really shows, and when they are unsafe.
Try 3 questions
1. According to gate control theory, why does rubbing a bumped elbow ease the pain?
- Rubbing pushes the swelling away from the joint
- Rubbing releases adrenaline straight into the elbow
- Touch signals dampen pain signals in the spinal cord
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Answer: Touch signals dampen pain signals in the spinal cord
Large touch fibers activate spinal interneurons that inhibit transmission from pain fibers, partly closing the 'gate' to the brain.
2. Gate control theory of pain, proposed in 1965, was developed by which pair of scientists?
- Watson and Crick
- Hodgkin and Huxley
- Melzack and Wall
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Answer: Melzack and Wall
Ronald Melzack and Patrick Wall proposed that spinal cord circuits modulate pain signals, transforming pain science and inspiring TENS.
3. Why does stubbing a toe produce a sharp pain followed by a slower, dull ache?
- The skin hurts first and the bone hurts later
- The brain replays the same pain signal twice
- Fast and slow nerve fibers carry separate signals
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Answer: Fast and slow nerve fibers carry separate signals
Thinly myelinated A-delta fibers carry quick, sharp first pain, while slower unmyelinated C fibers bring the later, aching second pain.
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