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a considerable amount of _sa-li'va_, (spittle.) This fluid is furnished by the salivary glands, situated in the vicinity of the mouth. The saliva moistens and softens the food, so that, when carried into the pharynx. it is passed, with ease, through the oesophagus into the stomach. 262. When the food has been properly masticated, (and in rapid eaters when it is not,) the soft palate is raised from the base of the tongue backward, so as to close the posterior opening through the nostrils. By a movement of the muscles of the tongue, cheeks, and floor of the mouth, simultaneous with that of the soft palate, the food is pressed into the upper part of the pharynx. -=-=-=-=-=-=-=-=-=-=-=-= 259-272. _Give the physiology of the digestive organs._ 259. What is necessary before food can nourish the body? 260. Describe how mastication is performed. 261. Of what use is the saliva in the process of mastication? 262. How is the food pressed into the pharynx? -=-=-=-=-=-=-=-=-=-=-=-= 263. When in the pharynx, the food and drink are prevented from passing into the trachea by a simple valve-like arrangement, called the _ep-i-glot'tis_. The ordinary position of this little organ is perpendicular, so as not to obstruct the passage of air into the lungs; but in the act of swallowing, it is brought directly over the opening of the trachea, called the _glot'tis_. The food, being forced backward, passes rapidly over the epiglottis into the oesophagus, where the circular band of muscular fibres above, contracts and forces the food to the next lower band. Each band relaxes and contracts successively, and thus presses the alimentary ball downward and onward to the stomach.[8] [8] The process of deglutition may be comprehended by analyzing the operation of swallowing food or saliva. _Observation._ If air is inhaled when the food or drink is passing over the glottis, some portions of it may be carried into the larynx or trachea. This produces violent spasmodic coughing, and most generally occurs when an attempt is made to speak while masticating food; therefore, never talk when the mouth contains food. -=-=-=-=-=-=-=-=-=-=-=-= 263. When the food is in the pharynx, how is it prevented from passing into the trachea, or windpipe? Describe how it is passed into the stomach? Give the observation. 264. Describe how the food in the stomach is converted into chyme. -=-=-=-=-=-=-=-=-=-=-=-= 264. When the food re
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