File:Physiology, hygiene and sanitation, an elementary textbook of physiology, with special attention given to hygiene and sanitation (1919) (14764889842).jpg

Identifier: physiologyhygien00heiz (find matches)
Title: Physiology, hygiene and sanitation, an elementary textbook of physiology, with special attention given to hygiene and sanitation
Year: 1919 (1910s)
Authors: Heizer, W. L. (W. Lucien), b. 1880
Subjects: Physiology Hygiene Sanitation
Publisher: Louisville, Ky., C.T. Dearing Printing Co., Incorporated
Contributing Library: The Library of Congress
Digitizing Sponsor: The Library of Congress

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one of our most useful of sensations, for by it thebody is often protected against injury. Without this sen-sation, the hand might be laid upon a hot stove and beseverely burned be-fore it would beremoved. Pain atonce sounds thealarm and thebody cells are sav-ed by reflex action. The pain oftoothache, illnessand of errors ineating or drink-ing, likewise, mayb e considered ablessing, becauseit calls attention toa condition whichought to be correct-ed. The cause ofpain and not painitself is to beavoided. Taste. The touch nerves are distributed over all thebody, but the special touch nerves which carry the mes-sages of taste are located only in the tongue. The taste nerves have special endings in the outer lay-ers of cells of the tongue, called taste buds. A substanceto be tasted must first be dissolved. The liquid containingsuch substance carries it between the taste cells, and aspecial impulse is carried by the sensory nerve to thebrain. If the tongue be wiped dry and a bit of sugar be
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The tongue, the organ of taste. 280 PHYSIOLOGY, HYGIENE AND SANITATION placed upon the tip of the tongue, it will not be i sweetuntil the saliva has dissolved it and carried it between thetaste cells. The sensation of taste may be sweet, sour, bitter,or salt. Sweet substances are best tasted on the tip of the tongue,while bitter ones are tasted most on the sides and backof the tongue. The sense of taste is useful; it acts as a guide in theselection of our food, and protects the body from foodwhich might contain dangerous poisons; It may, like-wise, be abused for often too much food is eaten becauseit tastes good. Spices and stimulants to the sense of tasteare to be avoided for this reason. Smell. A special pair of nerves supply the mucous mem-brane of the front part of the nose with nerve endingswhich carry impulses to the brain, which produce thesensation of smell. These endings lie between the cells ofthe mucous membrane and branch out into fine hair-likeendings. These nerve endings

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