Pain and temperature | Processing the Environment | MCAT | Khan Academy
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- เผยแพร่เมื่อ 24 ก.ย. 2013
- Explore our senses of pain & temperature. By Ron. Created by Ronald Sahyouni.
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I'm sorry but there's a few crucial mistakes that were made here
1) AB fibers mostly transmit touch sensation and have little to do with pain. Pain sensations are sent up through Aδ (sharp pain) and C (dull pain) fibers to the dorsal horn of the spinal cord, where the neuron ends. The sensation passes to a second neuron, crosses the midline, and ascends up to the brain where it is interpreted as pain
2) The narrator repeatedly referred to Aδ as "A-gamma" when in reality it is "A-delta"
I agree with the two previous comments (posted 2 years ago). Quoting "Neuroscience, 5th edition by D. Purves, p. 210":
Stimulation of the large, rapidly conducting A-alfa and A-beta axons in peripheral nerves does not elicit the sensation of pain. When investigators raise the stimulus intensity to a level that activates a subset of A-delta fibers, however, a tingling sensation or, if the stimulation is intense enough, a feeling of sharp pain is reported." If the stimulus intensity is increased still further, so that the small-diameter, slowly conducting C-fiber axons are brought into play, then subjects report a duller, longer lasting sensation of pain."
It's time that Khan remakes this video, these are fundamental mistakes that can have students possibly fail exams! :)
I am wondering, how the stimulus of the pain chooses the receptors, since there is all three types of nociceptors ? said it diffuses with the closest or nearest one? I don't think it's quite the true but I don't know why.....hehe
I see a lot of comments on this guy’s videos about mistakes but these videos are all referenced on the official AAMC mcat topic list thing so I don’t really know what to think lol
Also I looked all the information in my notes I took on this video and everything seems to be consistent with other sources
This video is fundamentally incorrect. It is presenting the Cartesian model of pain, where damaged tissue creates a pain response that is sent to the brain. This is simply not true. Pain does not equate to nociception, they are separate conditions. Nociception is the sensation of danger or damage, but does directly result in pain. Nociceptors as described send their stimuli to the brain, where the brain (in several locations) processes the data and may or may not begin a pain response. Pain is a sensation which is fully controlled by the brain, and may be present without any nociceptive trigger at all. There is no such thing as a pain pathway. Danger, or nociceptive signals are sent to the brain as described by the other commenters, and these signals may or may not contribute to a pain experience. This is obvious if you consider the time you noticed a bruise on your leg, but couldn't remember getting it. You physically damaged your body by slamming your knee into a table, but there was no pain present, because the brain decided that although there was tissue damage, there was no reason for a pain response. This is also why other seemingly benign stimuli might result in catastrophic pain, the brain determined the presence of danger, irrespective of a nociceptive signal. The Cartesian model of pain is deeply flawed and this has been known for many many years. In the last few decades, huge developments have been made in the fields of neurophysiology and pain science, and as such a biopsychosocial model of pain science has been developed. It's deeply disappointing that this video so misrepresents the literature.