The group of headaches known as migraines are thought to be caused by changes in the blood vessels in the scalp and the coverings of the brain. Typified by a pulsating, one-sided headache lasting up to three days, they are sometimes preceded by an aura involving sensations of flashing lights, loss of vision or tingling [...]

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Sneezing is a reflex action triggered by the presence of irritating material in the nose. Large particles cause direct physical stimulate; small particles act indirectly by including the release of irritating substances. In both cases, however, the reflex starts by stimulation of special receptors located between the cells lining the nose. When stimulated, these receptors [...]

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