| juras slīmiba |
15. Mar 2009|15:19 |
Seasickness
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In his book The Human Body, Isaac Asimov related the anecdote about a seasick passenger whom a steward cheerfully assured that nobody ever died from seasickness. The passenger muttered, "Please--it's only the hope of dying that's keeping me alive."
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Prevention and remedy
1. keeping one finger over one ear (blocking one ear). This stops the balancing liquid near your ears from moving around, therefore stopping the brain from detecting any motion sickness
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What purpose does motion sickness serve?
This is one aspect of the motion sickness syndrome that the neural mismatch theory is not able to explain. What purpose does motion sickness serve? Why should the end result of a neural mismatch or sensory conflict be vomiting, with all its attendant unpleasantness and neurohumoral consequences? This is a difficult teleological question to answer.
One postulated answer to this question lies in the theory put forward by Triesman, and supported by experimental work carried out by Money and Cheung (2,4,5,12,13,14,19). Triesman’s theory is that the discordant sensory information is interpreted by the central nervous system as evidence of neurophysiological dysfunction caused by poisoning (19). The most effective way of dealing with such an event is therefore to initiate vomiting to expel the toxin. Triesman’s theory is based on the premise that the orientation systems of the body, which subserve several functions such as postural control, stability of gaze etc., provide early warning of neurotoxicity. As such, the signs and symptoms of motion sickness can be regarded as the overt manifestations of the poison response (12).
There is some experimental evidence to support this theory. In one study, seven dogs were surgically labyrinthectomised (14). Post-operatively, none of the dogs suffered motion sickness on a provocative motion test, and there was no emetic response to a series of poisons administered to the animals. The researchers concluded that the vestibular system facilitates the emetic response to poisons, and that this mechanism is the basis of motion sickness.
The theory that motion sickness is the result of activation, by motion, of the mechanism that is normally responsible for inducing vomiting in response to poisons is an intriguing and thought-provoking notion, that seems to have some basis experimentally. |
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