The Physiology of Digestion Considered With Relation to the Principles of Dietetics

CHAPTER I.. Introductory Remarks.

INTRODUCTORY REMARKS.

Waste or loss of substance always attendant on action--In the vegetable and animal kingdoms waste is greater than in the physical--Living bodies are distinguished by possessing the power of repairing waste--Vegetables, being rooted in one place, are always in connection with their food--Animals, being obliged to wander, receive their food at intervals into a stomach--Nutrition most active when growth and waste are greatest--In vegetables the same causes which increase these processes also stimulate nutrition--But animals require a monitor to warn them when food is needed--The sense of Appetite answers this purpose--The possession of a stomach implies a sense of Appetite to regulate the supplies of food, 1–10

CHAPTER II.. The Appetites of Hunger and Thirst.

THE APPETITES OF HUNGER AND THIRST.

Hunger and Thirst, what they are--Generally referred to the stomach and throat, but perceived by the brain--Proofs and illustrations--Exciting causes of hunger--Common theories unsatisfactory--Hunger sympathetic of the state of the body as well as of the stomach--Uses of appetite--Relation between waste and appetite--Its practical importance--Consequences of overlooking it illustrated by analogy of the whole animal kingdom--Disease from acting in opposition to this relation--Effect of exercise on appetite explained--Diseased appetite--Thirst--Seat of Thirst--Circumstances in which it is most felt--Extraordinary effects of injection of water into the veins in cholera--Uses of thirst, and rules for gratifying it, 11–39

CHAPTER III.. Mastication, Insalivation, and Deglutition.

MASTICATION, INSALIVATION, AND DEGLUTITION.

Mastication--The teeth--Teeth, being adapted to the kind of food, vary at different ages and in different animals--Teeth classed and described--Vitality of teeth and its advantages--Causes of disease in teeth--Means of protection--Insalivation and its uses--Gratification of taste in mastication--Deglutition, 40–57

CHAPTER IV.. Organs of Digestion--the Stomach--the Gastric

ORGANS OF DIGESTION--THE STOMACH--THE GASTRIC JUICE.

Surprising power of digestion--Variety of sources of food--All structures, however different, formed from the same blood--General view of digestion, chymification, chylification, sanguification, nutrition--The stomach in polypes, in quadrupeds, and in man--Its position, size, and complexity, in different animals--Its structure; its peritoneal, muscular, and villous coats; and uses of each--Its nerves and bloodvessels; their nature, origins, and uses--The former the medium of communication between the brain and stomach--Their relation to undigested food--Animals not conscious of what goes on in the stomach--Advantages of this arrangement--The gastric juice the grand agent in digestion--Its origin and nature--Singular case of gunshot wound making a permanent opening into the stomach--Instructive experiments made by Dr Beaumont--Important results, 58–108

CHAPTER V.. Theory and Laws of Digestion.

THEORY AND LAWS OF DIGESTION.

Different theories of Digestion--Concoction--Fermentation --Putrefaction--Trituration--Chemical solution--Conditions or laws of digestion--Influence of gastric juice.--Experiments illustrative of its solvent power--Its mode of action on different kinds of aliment--beef, milk, eggs, soups, &c.--Influence of temperature--Heat of about 100° essential to digestion.--Gentle and continued agitation necessary--Action of stomach in admitting food--Uses of its muscular motion--Gastric juice acts not only on the surface of the mass, but on every particle which it touches--Digestibility of different kinds of food--Table of results--Animal food most digestible--Farinaceous next--Vegetables and soups least digestible--Organs of digestion simple in proportion to concentration of nutriment--Digestibility depends on adaptation of food to gastric juice more than on analogy of composition--Illustrations.--No increase of temperature during digestion--Dr Beaumont’s summary of inferences, 109–151

CHAPTER VI.. Chylification, and the Organs Concerned in It.

CHYLIFICATION, AND THE ORGANS CONCERNED IN IT.

Chylification--Not well known--Organs concerned in it--The intestinal canal--Its general structure--Peritoneal coat--Mesentery--Muscular coat--Uses of these--Air in intestines--Uses of--Mucous coat--Analogous to skin--The seat of excretion and absorption--Mucous glands--Absorbent vessels--Course of chyle towards the heart--Nerves of mucous coat--Action of bowels explained--Individual structure of intestines--The Duodenum--Jejunum--and Ileum--Liver and pancreas concerned in chylification--Their situation and uses--Bile, its origin and uses--The pancreas--Its juice--The jejunum described--The ileum--Cœcum--Colon--and Rectum--Peristaltic motion of bowels--Aids to it--Digestion of vegetables begins in stomach but often finished in the bowels--Illustration from the horse--Confirmation by Dupuytren, 152–183

PART II.. The Principles of Dietetics Viewed in Relation

THE PRINCIPLES OF DIETETICS VIEWED IN RELATION TO THE LAWS OF DIGESTION.

CHAPTER I.

TIMES OF EATING.

The selection of food only one element in sound digestion--Other conditions essential--Times of eating--No stated hours for eating--Five or six hours of interval between meals generally sufficient--But must vary according to circumstances--Habit has much influence--Proper time for breakfast depends on constitution, health, and mode of life--Interval required between breakfast and dinner--Best time for dinner--Circumstances in which lunch is proper--Late dinners considered--Their propriety dependent on mode of life--Tea and coffee as a third meal, useful in certain circumstances--Supper considered--General rule as to meals--Nature admits of variety--illustrations--but requires the observance of principle in our rules, 187–217

CHAPTER II.. On the Proper Quantity of Food.

ON THE PROPER QUANTITY OF FOOD.

Quantity to be proportioned to the wants of the system--Appetite indicates these--Cautions in trusting to appetite--General error in eating too much--Illustrations from Beaumont, Caldwell, Head, and Abercrombie--Mixtures of food hurtful chiefly as tempting to excess in quantity--Examples of disease from excess in servant-girls from the country, dressmakers, &c.--Mischief from excessive feeding in infancy--Rules for preventing this--Remarks on the consequences of excess in grown persons--Causes of confined bowels explained--And necessity of fulfilling the laws which God has appointed for the regulation of the animal economy inculcated, 218–250

CHAPTER III.. Of the Kinds of Food.

OF THE KINDS OF FOOD.

What is the proper food of man?--Food to be adapted to constitution and circumstances--Diet must vary with time of life--Diet in infancy--The mother’s milk the best--Substitutes for it--Over-feeding a prevalent error--Causes which vitiate the quality of the milk--Regimen of nurses--Weaning--Diet after weaning--Too early use of animal food hurtful--Diet of children in the higher classes too exciting--and produces scrofula--Mild food best for children--Incessant eating very injurious--Proper diet from childhood to puberty--It ought to be full and nourishing but not stimulating--Often insufficient in boarding-schools--Diet best adapted for different constitutions in mature age--Regimen powerful in modifying the constitution, mental as well as physical--Farther investigation required, 251–287

CHAPTER IV.. Conditions to Be Observed Before and After Eating.

CONDITIONS TO BE OBSERVED BEFORE AND AFTER EATING.

General laws of organic activity apply to the stomach as well as to other parts--Increased flow of blood towards the stomach during digestion--Hence less circulating in other organs--and consequently less aptitude for exertion in them--Bodily rest and mental tranquillity essential to sound digestion--Rest always attended to before feeding horses--Hence also a natural aversion to exertion immediately after eating--Mischief done by hurrying away to business after meals--Severe thinking hurtful at that time--Playful cheerfulness after dinner conducive to digestion--The mind often the cause of indigestion--Its mode of operation explained--Also influences nutrition--Illustration from Shakspeare--Importance of attending to this condition of health enforced, 288–303

CHAPTER V.. On Drinks.

ON DRINKS.

Thirst the best guide in taking simple drinks--Thirst increased by diminution of the circulating fluids--The desire for liquids generally an indication of their propriety--Much fluid hurtful at meals--Most useful three or four hours later--The temperature of drinks is of consequence--Curious fall of temperature in the stomach from cold water--Ices hurtful after dinner--Useful in warm weather, when digestion is completed and caution used--Cold water more dangerous than ice when the body is overheated--Tepid drinks safest and most refreshing after perspiration--Kinds of drink--Water safe for every constitution--Wine, spirits, and other fermented liquors, too stimulating for general use, but beneficial in certain circumstances--Test of their utility, 304–323

CHAPTER VI.. On the Proper Regulation of the Bowels.

ON THE PROPER REGULATION OF THE BOWELS.

Functions of the intestines--The action of the bowels bears a natural relation to the kind of diet--Illustrations--And also to the other excretions--Practical conclusions from this--Different causes of inactivity of bowels--Natural aids to intestinal action--General neglect of them--Great importance of regularity of bowels--Bad health from their neglect--especially at the age of puberty--Natural means preferable to purgatives--Concluding remarks, 324–339

INDEX, 341–350

WOOD-CUTS.

Under-jaw, 41. Thoracic and Abdominal Viscera, 66. Human Stomach, 67. Stomach of a ruminating animal, 69. Villous Coat of the Stomach, 75. Opening into the stomach of Alexis St Martin, 88. Abdominal Viscera, 155. Transverse section of the Abdomen, 157. Lacteals and Thoracic Duct, 163. Thoracic Duct, 166. Contents of the Abdomen after removal of the Intestines, 171. Mucous Coat of the Duodenum, 172.

PREFACE.

The present volume is essentially a continuation of the work first published about two years ago, under the title of “The Principles of Physiology applied to the Preservation of Health and to the Improvement of Physical and Mental Education;” and its object is the same--namely, to lay before the public a plain and intelligible description of the structure and uses of some of the more important organs of the human body, and to shew how information of this kind may be usefully applied, not only in the prevention of suffering, but in improving the physical, moral, and intellectual condition of man.

In “The Principles of Physiology,” the structure and functions of the skin, muscles, bones, lungs, and nervous system, the laws or conditions of their healthy action, and the unsuspected origin of many of their diseases in infringements of these laws, were explained in succession at considerable length; and the means by which their health and efficiency might best be secured were pointed out. It was stated that, in selecting these organs as subjects for discussion, I had been guided by the desire to notice in preference those functions which are most influential in their operation on the general system, and at the same time least familiarly known; and that, if the attempt to convey the requisite information in a manner suited to the general reader should prove successful, I would afterwards prepare a similar account of others, in the right understanding and management of which our interest is not less deeply involved, but in regard to which much ignorance continues nevertheless to prevail, even among the most liberally educated classes of society.

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