Class-book of physiology : for the use of schools and families : comprising the structure and functions of the organs of man, illustrated by comparative reference to those of inferior animals . xedwith the food, and the work of digestion becomes corres-pondingly more difficult. In this country, impaired diges-tion and loss of general health is a frequent result ofrapid eating. 156. When mastication hasbeen completed, the food is trans-mitted in successive portions tothe stomach by the act of degluti-tion or swallowing. The food isfirst collected into a ball or massby the action of the muscles
Class-book of physiology : for the use of schools and families : comprising the structure and functions of the organs of man, illustrated by comparative reference to those of inferior animals . xedwith the food, and the work of digestion becomes corres-pondingly more difficult. In this country, impaired diges-tion and loss of general health is a frequent result ofrapid eating. 156. When mastication hasbeen completed, the food is trans-mitted in successive portions tothe stomach by the act of degluti-tion or swallowing. The food isfirst collected into a ball or massby the action of the muscles ofthe cheeks and tongue, and isconveyed back against a sort ofmovable curtain (the vail of thepalate), which hangs from thesides of the palate so as to touchthe tongue by its lower border,and makes the mouth a closedcavity. {Fig. 31.) The instantthe food is brought against thispartition, it opens, and allows thefood to pass into the oesophagus or food-pipe receives the morsel from the When is the saliva secreted 1 How is the secretion of saliva affected byfevers? How is digestion affected by an imperfect mastication of the food?Plow is the food transmitted to the stomach ? 6. Jig. 31.—Suction of Mouth andThroat.—a, vail of the palate; b,pharynx; c, oesophagus; </, trachea;e, thyroid gland; /, larynx; g, sali-vary gland; h, tongue. 74 CLASS-BOOK OF PHYSIOLOGT. pharynx, and forces it along to the stomach by the alternatecontraction of its successive portions. The undulatingmovement produced by the contractions may be readilyobserved in the oesophagus of a horse while in the act ofdrinking. 157. The form and size of the stomach varies in differ-ent animals, according to the nature of the food to bedigested. It is found in its simplest condition in the classof polypes,of which the hydra {fig. 14) is an example. Inthis animal, the stomach is merely a bag or sac with oneopening, as represented in fig. 4, Pl. VII. Around thiaorifice to the stomach are from six to te
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