Pancreatic juice

“ On demand, pancreatic juice is manufactured in the pancreas and poured into the intestine just beyond the pylorus through a small duct—the duct of Wirsung. Secretion is started by contact of the acid contents of the stomach with the mucous membrane of the small intestine, so that as soon as the acid chyme passes through the pyloric sphincter32 there commences an outflow of pancreatic juice into the intestine. While acid is plainly the inciting agent in this secretory process, its action is indirect. ”

“ Meat is almost all digested in the stomach by the gastric juice, which changes it into peptone. It is needless to say that it should be thoroughly masticated that there may be no delay in the prompt action of the gastric juice upon it. If any part passes into the intestine undigested, the process is continued by the trypsin of the pancreatic juice. The peptone is absorbed as peptone and after it passes through the inner coating of the intestines, it is changed back to protein and carried by the blood and lymph to all tissues of the body, where it is used for growth and repairs. ”

“ Second, The gastric juice; secreted in the inner or third lining of the stomach,—an acid, and powerful enough to dissolve all the fiber and albumen of flesh food.
Third, The pancreatic juice; secreted by the pancreas, which you know in animals as sweetbreads. This juice has a peculiar influence upon fats, which remain unchanged by saliva and gastric juice; and not until dissolved by pancreatic juice, and made into what chemists call an emulsion, can they be absorbed into the system.
Fourth, The bile; which no physiologist as yet thoroughly understands. ”

“ That of the liver is largely excretion or refuse from the blood without direct action on the food, but it enables the pancreatic juice to do its work by making the food again alkaline, and stimulates the muscular coats of the intestine to force its contents along. That of the pancreas is the most important digestive fluid in the body, containing many ferments; it acts alike on proteids, carbohydrates, and fats—in fact, digests everything—so that the rest of the long tube is freed from any more laborious duty than absorbing them as they pass. ”

“ The pancreatic juice is secreted by the pancreas, an elongated organ situated just behind the stomach, and its purpose is to act upon the fatty portions of the food and to render them possible of absorption from the intestines along with the other parts of the food nourishment. ”

“ The pancreas is a gland near the stomach; it secretes the juice known as pancreatic and pours it into the duodenum, or small intestine, which—some ten or fifteen feet in length, is folded about it. To prevent intestinal indigestion there must be an abundant flow of pancreatic juice, and this flow is stimulated by the vinegar in the salad we eat and other acids in our food. ”

“ There is none in the mouth; one in the stomach works only on fat in the state of emulsion; the most powerful is found in the pancreatic juice. Since fat cannot be digested in the mouth nor to any great extent in the stomach, it is bad to have food coated with it, for the protein and carbohydrates will have to wait till the fat is digested away, before they can be digested; that is, till the intestine is reached. This is one reason why pastries and fried foods are hard to digest.
Digestion of protein.—There are no enzymes in the mouth acting on protein. ”

“ It is even conceivable that the whole digestion may depend upon the stimulating properties of acids, since the pancreatic juice exerts a ferment action upon all the constituents of the food. In this way acids may either assist digestion in the stomach where too little gastric juice is present, or bring about vicarious digestion by the pancreas where it is wholly absent. ”

“ In cream the fat is held in the form of an emulsion which allows it to mingle freely with water. As previously stated, each atom of fat is surrounded with a film of casein. The gastric juice has no more power to digest casein than it has free fat, and the little particles of fat thus protected are carried to the small intestines, where the pancreatic juice digests them, and on their way they do not interfere with the stomach digestion of other foods, as the presence of butter and other free fats may do. ”

“ Expressed in different language, pancreatic juice as it is secreted by the gland does not contain ready-formed trypsin; it does contain, however, an inactive pro-enzyme, which, under the influence of a specific substance contained in the intestinal mucous membrane, known as enterokinase, is transformed into the active enzyme trypsin. There is thus seen another suggestive example of the close physiological relationship between the small intestine and the activity of the pancreatic gland, or its secretion.
The chemical changes taking place in the small intestine are many and varied. ”

“ Not only is this the case with the secretion from the glands surrounding the mouth, but the pancreas which is concerned in a later stage of digestion is a gland so similar to the salivary glands that in ordinary cookery both are dressed and served as ‘sweetbreads;’ the ‘pancreatic juice’ is a liquid closely resembling saliva, and contains a similar diastase, or substance that converts starch into dextrin, and from dextrin to sugar. ”

“ Now, we do find in the liver itself and in the bile a ferment having the same diastatic power as the pancreatic juice, but it does not appear in such quantities as one would expect if the whole of the pancreatic ferment were simply reëxcreted by the liver along with the bile, and, as we have no evidence that the ferment is destroyed during its action in the intestine, we are naturally led to think that it may undergo a change in the liver, the converse of that which it undergoes in the pancreatic gland during the process of secretion. ”

“ The exclusive milk diet is the best starting-point in feeding a patient suffering from acute or chronic indigestion. In addition to the fact that milk has all the elements of a perfect food, it contains sugar and fat in the most favorable condition for absorption; the casein of milk alone requires transformation into peptone. The pancreatic juice has the greatest activity in its effect upon milk, as is easily demonstrated by the artificial digestion of milk by pancreatic extract. In milk, therefore, we find a most easily digestible and most highly nutritious food for such cases. ”

“ The peculiar and very active diastatic ferment of pancreatic juice converts starch into sugar very readily. Farinaceous articles of diet can be added to milk with advantage. Digestion takes place more slowly and more thoroughly in consequence, and an additional article of nutriment is obtained. Thus, milk can be diluted with a thick gruel of barley or oatmeal, or some of the best of the various artificial foods can be stirred in. ”

“ He decided that these were secretory (conglomerate) rather than lymphatic (conglobate) glands, and believed their secretion had digestive properties, active in the lower ileum at a point where the pancreatic juice must become exhausted.
In 1683, Johann Conrad Brunner (1653-1727) , of Germany, published the results of experiments which he had made in exsecting the pancreas and ligating the pancreatic duct in dogs. As the dogs did not manifest any disturbance of digestion or nutrition, he argued that the importance attached by Sylvius and de Graaf to pancreatic digestion was unfounded. ”

“ The white fibres swell when treated with weak acetic acid, and are readily dissolved by peptic digestion but not by pancreatic. The yellow elastic fibres, on the other hand, are unaffected by acetic acid and resist the action of gastric juice for a long time, but are dissolved by pancreatic juice. ”

“ Of Glucoses the best example is dextrose = C6H12O6, H2O, which can be seen crystallised in dried raisins; it only possesses one-third the sweetening power of sucrose. Starchy food becomes changed into glucose by the action of saliva and pancreatic juice in the alimentary canal. ”

“ The gastric juice is partly prevented from secreting and that which is secreted is unhealthy, the ducts of the liver and pancreatic gland are prevented from performing their healthy functions and consequently the food is not taken in due quantity to nourish the system, and what is taken is not properly digested, for the want of a free and healthy action of the digestive functions. ”

“ The diet must be simple and digestible, and if an arrest of the pancreatic secretion be indicated by the appearance of fat in the stools, an effort should be made to supply the deficiency. For this purpose pancreatin, prepared by precipitation by alcohol from a watery extract of a calf's or pig's pancreas, may be used.1 The pancreatin may be given in doses of from five to fifteen grains, in the form of a pill or in capsules, and at an interval of two hours after food is taken, or the same quantity of pancreatin may be added to the food a few moments before it is eaten. ”

“ It is our custom to apply these extracts to every case where we want to increase bodily weight by a better assimilation of the food. Especially in cases where we have given much milk do we find that it is much better tolerated by the addition of these extracts to the food. We have also found, by experiments on ourselves, that the feeling of oppression and heaviness in the stomach after hearty meals, especially of indigestible food, has been much improved by the use of two 448to three of these pancreatic tablets. ”

“ The carbohydrates include sugars, starches, cellulose, and the fibers of plants. Potatoes, sago, farina, and arrowroot are rich in them. Fats should be used with caution in disease, because they retard the formation of hydrochloric acid, which excites the pancreatic secretion, an important factor in digestion. Man can live better without a stomach than without a pancreas. Physicians realize that they must rely on diet rather than drugs to cure indigestion, as the food varies in its proportion of fat, protein, and carbohydrates ”

“ Even in aged persons we have noted easier digestion and the disappearance of digestive trouble after two or three tablets of the extract of pancreas taken immediately after dinner and supper. In cases of liver and gall-stone troubles, where previously there was a considerable loss of bodily weight, in nearly every case after pancreatic treatment there was no more falling off in the weight, and in some instances we have even found a considerable increase in weight. ”

“ After the salivary glands the most important structure for the digestion of starches in the animal economy is the pancreas. It was early evident, however, that the pancreatic secretion effected more than the conversion merely of starch into sugar. Its most important rôle, that of influencing the digestion and absorption of fats, was only recognized as the result of a classical observation of Bernard's upon the rabbit. He noticed that fat introduced into the digestive tract of a rabbit undergoes no change until it has advanced a considerable distance beyond the stomach. ”

“ Nature has provided for this by causing another gland farther down the canal, just beyond the stomach, called the pancreas, to pour into the food tube a juice which is far stronger in sugar-making power than the saliva, and this will readily deal with any starch which may have escaped this change in the mouth. Moreover, this "sugaring" of starch goes on in the stomach for twenty to forty minutes after the food has been swallowed.
Starchy foods, like bread, biscuit, crackers, cake, and pastry, are really the only ones which require such thorough and elaborate chewing as we sometimes hear urged. ”

“ It excites the sides of the stomach, and by this promotes the secretion of the juice by which food is dissolved. It often occurs, that if but a minute quantity of fat has been taken, it envelops the food in the stomach; and as the gastric juice dissolves fat only with great difficulty, this food often remains undigested in the stomach, and nutrition then is carried on but defectively. Digestion, therefore, may be greatly improved, if the stomach is so affected as to secrete a greater quantity of gastric juice ”

“ When the juice is examined as regards its digestive activity, it is found that with meat the most active juice is secreted within the first hour, with bread in the second and third hours, and with milk in the sixth hour. According to the nature of the food, the stomach seems to be stimulated to form a secretion which will best serve its purpose and give the minimum of waste. It thus works economically. The principal ferment found in the gastric juice is pepsin, a ferment which acts only in the presence of a mineral acid. ”

“ If the diabetic tendency of an individual is marked, diabetes may develop, in very early life. The pancreas here is too weak to withstand the normal functional strain of growth. When this is the case, the disease is of extreme severity. If the diabetic tendency is slight, it may not show itself except as the result of long continued overeating. If the pancreatic islands are functionally strong, they withstand infections and injury from disease or poor blood supply; if weak, they fail and diabetes results. ”

“ The intestinal secretions are mainly from the crypts of Lieberkühn, and their action in the digestive process is probably comparatively unimportant, but in some animals they have been found to digest starch. It will be observed that of all these secretions that which digests the largest number of nutritive principles is the pancreatic. It digests all those which are essential to the maintenance of life except fat, and it aids the bile in emulsifying fat. ”