A text-book on anatomy, physiology, and hygiene, for the use of schools and colleges / by John C. Draper.

  • Draper, John C. (John Christopher), 1835-1885.
Date:
[1894], ©1894
Catalogue details

Licence: Public Domain Mark

Credit: A text-book on anatomy, physiology, and hygiene, for the use of schools and colleges / by John C. Draper. Source: Wellcome Collection.

Provider: This material has been provided by the Francis A. Countway Library of Medicine, through the Medical Heritage Library. The original may be consulted at the Francis A. Countway Library of Medicine, Harvard Medical School.

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    made of the pollen of a reed; also Dika bread, from Africa, which has the appearance of Castile soap when cut. There is also a specimen, said to have been found in Lake Zurich, and supposed to belong to the stone period, but there are doul >ts regarding its history. The salts are phosphate of lime and chloride of sodium, or common salt. The first is employed in the nutrition of the bones, and the second, as we have seen, is essential to the prop- er conduction of digestion, furnishing hydrochloric acid for the gastric juice, and soda for the bile and pancreatic fluid. LECTURE XII. DIGESTION. Mastication.—Action of Saliva.—Action of Gastric Juice.—Formation and Properties of Chyme and Chyle.—Action of Pancreatic Juice on Hydro-carbons and Carbo-hydrates.— Old and new Theories of Diges- tion.—Digestibility of various Articles of Pood.—Effect of Quantity on the Pate of Digestion.—Indigestion as a Disease and a /Symptom.-—Ef- fect of Nature of Diet on length of Intestine.—Digestive Apparatus in certain Animals. Having described the digestive apparatus, and examined into the nature of the ingesta and digestive juices, we now pass to the detailed explanation of the processes to which the food is subjected before it is properly prepared for absorption by the blood-vessels and lacteals. The first operation to which it is submitted is mastication, during which it is not only thoroughly subdivided, but also mixed with saliva and air. It is then swallowed, and, passing into the stomach, the ptyaline of the saliva commences immedi- ately at the existing temperature to convert starch into glucose or sugar, and then into lactic acid. While this is going on in the interior of the mass, the gastric juice is acting with energy on its exterior, the hydrochloric acid,by the aid of the pepsin, dissolving the nitrogenized substances, albumen, fibrin, casein, and gluten, converting them into soluble peptones. Gradually, by the agency of the saliva and gastric juice, the mass is broken up, and a fluid called chyme produced, which is of a tawny yel- low color, and contains the oils and fats undissolved. What is the use of phosphate of lime ? For what purpose is chloride of sodium employed in the system? What is accomplished by mastication? What is the action of the gastric juice? Where is its action carried on? What are peptones?