b. Nervo-muscular Intestinal Sedatives.-The drugs which arrest the movements of the bowel, either directly or through the nerves, include Opium, Morphia, and Lead, which diminish peristalsis, and may even completely paralyse the bowel. Substances which form a protective lining on the mucosa, and antacids indirectly produce the same effect, by diminishing the irritation of the contents. Bismuth, Chalk, Lime, and Alkalies act, partly at least, in this way. All are astringents.

6. Cholagogues

Cholagogues. Following naturally on the last class of purgatives comes a group which act indirectly upon the muscular coat, by increasing the flow of its natural stimulant, the bile. These substances are known as cholagogues (The Intestine Part 3 5 bile, and The Intestine Part 3 6 I cause to flow). As will be explained in the next chapter, they either act directly upon the liver-cells and gallbladder-direct cholagogues; or sweep out of the body what bile is lying in the intestine, and thus indirectly stimulate a fresh secretion-indirect cholagogues. Direct cholagogues may be illustrated by Podophyllin, Rhubarb, and Sulphate of Soda; indirect cholagogues are chiefly Mercurials. It will be observed that cholagogues and purgatives have complex associations with each other: most purgatives are probably indirect cholagogues; many purgatives happen to be also direct cholagogues; and all cholagogues exert a certain amount of purgative effect, inasmuch as they increase the flow of the natural intestinal stimulant.

We do not deliberately employ anticholagogue measures, for checking the flow of bile. Opium possesses this action.

Enemata (The Intestine Part 3 7 I inject). Many of the remedies just mentioned may be adminstered by enema, that is, injected into the rectum. (1) Food, such as beef tea, eggs, gruel, and milk, and alcoholic stimulants, constitute nutrient and stimulant enemata. (2) Intestinal stimulants may be given as purgative enemata, chiefly Castor Oil, Olive Oil, and the officinal Enemata of Aloes and Sulphate of Magnesia. (3) Enema Opii is a most valuable sedative and astringent preparation. Solutions of Sulphate of Zinc or Copper, Nitrate of Silver, Alum, and Decoctum Q,uercu.s, are also astringent. Enema Tabaci is now very rarely used as a powerful depressant enema. The rectum may be mechanically emptied by simple enemata, such as warm water, warm soap and water, and thin gruel, which soften the faeces and stimulate the parts. Besides these we possess anthelmintic enemata, which remove worms, such as the Enema Terebinthinae, Enema Aloes, and an enema of bitter infusions, or salt and water. Ice-cold water may be injected into the rectum as an antipyretic enema, i.e. to reduce the temperature, and as a styptic enema in haemorrhage.

III. Pathological Relations

As far as our present purpose is concerned, the disturbances of the intestine, independently of its digestive function, which has been already discussed, are chiefly two, namely: excessive action, the striking phenomenon of which is diarrhoea, and defective action, characterised by constipation.

1. Excessive Intestinal Action

Excessive Intestinal Action. Diarrhoea, as we have seen, is generally referable to gastric or duodenal dyspepsia. The ultimate cause is most commonly improper food, including the various irritant substances which may be admitted along with it, such as unwholesome drinks, the organisms of putrefaction, and the poisons of typhoid fever, dysentery, and cholera. Irritant poisons have the same effect. Certain intestinal irritants are generated in the body itself, such as urea, the poison of gout (chiefly uric acid), and the poison of pyaemia. Nervous disturbances may produce diarrhoea, for example, anxiety and fear. Disorders of the general and abdominal circulation are frequently attended by a watery flow or flux from the bowels, as in diseases of the liver and heart, or as the result of chill. Lastly may be mentioned organic disease of the intestines. The student must carefully note that diarrhoea, although of much importance in itself and as a cause of further disorder, is but a symptom, the anatomical condition on which it depends varying greatly.

In connection with excessive activity of the intestines must be taken here certain conditions, such as hernia, peritonitis, and perforation of the bowel, in which any peristaltic movement of the intestine, however slight, must be considered excessive because highly dangerous, and in which paralysis of the intestine for the time being is urgently required.

2. Deficient Intestinal Action

Deficient Intestinal Action. Constipation is even more common than diarrhoea, and is peculiarly apt to appear in a chronic form. Of its causes, we may select as illustrative examples certain kinds of food, already noticed; chronic gastric and duodenal dyspepsia, especially in connection with biliary disorder; sedentary or careless habits; and certain specific substances, such as lime and lead, admitted in the food or otherwise. Habitual constipation is generally due to loss of irritability and vigour of the nervo-muscular structures from very chronicity of the state and neglect of regular defaecation; to impairment of the general health by sedentary occupations, foul air, etc.; to a variety of obscure causes, commonly referred to as locality, and change of habits; and to certain organic diseases of the bowel. The most severe and obstinate cases of constipation are caused by paralysis of the bowel in disease of the spinal cord and lead-poisoning. Although constipation, like diarrhoea, is but a symptom, and must be treated as such, its unfavourable effects on digestion, sanguification, and the functions generally, are almost endless.

Along with constipation must be considered a class of cases where disease of the digestive organs, liver, heart, lungs, general circulation, brain, blood, or kidneys, demands free evacuation of the bowels, and, it may be, even a hydragogue or cathartic action, chiefly as a means of unloading the circulation or of evacuating excrementitious substances. Frequent reference will be made to this application of purgation under the several organs in the following chapters.