. Human physiology : designed for colleges and the higher classes in schools, and for general reading. ether. The transverse fibres, when they con-tract, diminish the capacity of the stomach transversely. Andthe oblique fibres modify these two motions by their obliqueaction. 83. By the combined chemical and mechanical action of thestomach, its contents are, after a little time—in three or fourhours—reduced to an uniform, greyish, semi-fluid mass, calledchyme. While this process has been going on, the communi-cation between the stomach and the intestines has been entirelyclosed by a valve, call
. Human physiology : designed for colleges and the higher classes in schools, and for general reading. ether. The transverse fibres, when they con-tract, diminish the capacity of the stomach transversely. Andthe oblique fibres modify these two motions by their obliqueaction. 83. By the combined chemical and mechanical action of thestomach, its contents are, after a little time—in three or fourhours—reduced to an uniform, greyish, semi-fluid mass, calledchyme. While this process has been going on, the communi-cation between the stomach and the intestines has been entirelyclosed by a valve, called the pylorus. This is represented at 5,in Fig. 14, which presents a view of the inside of the valve is made of a fold of both the mucous and muscularcoats of the stomach. It is a very faithful sentinel, as is indi-cated by its name, which is derived from two Greek words, sig-nifying to guard the gate. It will not ordinarily permit anyundigested food to pass it. While the process of digestion is 62 HUMAN PHYSIOLOGY. The pylorus. A sentinel. On duty only during digestion. FIG. INTERIOR OF THE STOMACH AND SMALL INTESTINE. going on, the motions produced by the muscular fibres causathe contents to move about, and of course they are thrownagainst the pylorus, as well as any other part of the the valve remains closed, until some portion comes againstit that is thoroughly changed to chyme, and is therefore fit topass on into the intestine. It then opens to let this pass, andit does so for any other portions that have become the conclusion of the digestion of a meal, small quan-tities pass at first, and after a while, the contents pass quiterapidly through the valve. 84. Although this sentinel-valve thus performs its duty sofaithfully in relation to nutritive substances, it seems to let othersubstances pass very readily. Solid substances, swallowed bymistake, as buttons, pieces of money, the pits and skins of vari-ous fruits, often pass t
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