Inhibitory Impulses Research Articles

Treatment of Ileus by Splanchnic Anesthesia. An Experimental Study.

Markowitz and Campbell have shown that spinal anesthesia will relieve paralytic ileus produced in experimental animals. Believing that in these cases inhibitory impulses were transmitted to the intestines by way of the splanchnic and that spinal anesthesia produced a splanchnic block, we decided that spinal anesthesia was dangerous and unnecessary, as the same results could be produced by splanchnic anesthesia by the Kappis technic. Twenty-four dogs were used in this experiment to see if peristalsis could be reestablished in experimentally produced ileus. Upon opening the abdomen of the dog and exposing the intestine there results a physiological ileus. The number of dogs used in this experiment was 14. This type of ileus was easily overcome by splanchnic block with 1% novocain by the Kappis method, producing active peristalsis in the quiescent intestine. The peristaltic waves, after splanchnic anesthesia, were recorded by kymographic tracings. The next experiment was the production of a chemical ileus and the reestablishment of peristalsis in this chemically produced ileus. Five dogs were used in this experiment. The ileus was produced by injecting into the abdominal cavity, through the abdominal wall, iodine and potassium iodide solution. Observations were then made fluoroscopically and radiographically by contrast meal introduced into the gastro-intestinal tract. After the development of the ileus, splanchnic anesthesia was produced. Fluoroscopical and radiographical observations demonstrated the return of peristalsis in the ileus, which readily returned to the normal condition, showing that a chemical ileus could easily be overcome and peristalsis reestablished by splanchnic anesthesia.

The clinical behavior of the normal and the diseased gall bladder

The serious consequences of disease of the gall bladder far exceed its functional importance so that even when slightly diseased its removal is justifiable when the symptoms have reached the stage of pain and distress. The gross and histologic anatomy of the organ favor stasis and retard recovery from infection. Filling of the gall bladder is possible only by an increase in intraductal pressure resulting from tonic closure of the lower end of the common duct which forces bile into the cystic duct. When the sphincter of Oddi is incompetent the gall bladder can not fill. The gall bladder empties through the cystic duct by its own muscular power which is sufficient to overcome intraductal pressure as well as the resistance of the sphincter. Food is the normal and most efficient stimulus to contraction of the gall bladder. The vagus or parasympathetic is the motor nerve for the gall bladder and inhibitory for the sphincter of Oddi. The sympathetic supplies inhibitory impulses to the gall bladder and motor impulses to the sphincter. The symptoms of cholecystitis can be explained on the basis of pathologic physiology. The phenomena of the findings of cholecystography are directly related to the mechanism of the sphincter of Oddi and pertain only indirectly to the condition of the gall bladder. The physiologic effects of disease of the gall bladder are delay in emptying, accumulation of highly concentrated residual bile and failure to acidify the bile, factors which favor the formation of stones. Equally important effects are dilatation of the ducts and hypotonus of the sphincter at the lower end of the common duct. The latter phenomena also occur when the gall bladder has been removed.

The Mechanism of Voluntary Muscular Fatigue

The Mechanism of Voluntary Muscular Fatigue

BILIARY, PANCREATIC AND DUODENAL STUDIES

I shall first give a brief sketch of the progress of opinion on the function of the gallbladder. In 1893, Doyon1carried out experiments on the gallbladder of dogs in situ in a manner which convinced him that there were definite contractions of the organ, and that these contractions were increased by stimulation of the sympathetic nerves. Later Courtade and Guyon2demonstrated that the vagus also contained motor fibers to this organ. In 1905, Bainbridge and Dale,3two of England's foremost physiologists, published some conclusive observations, gallbladder shows rhythmic variations in volume. The rhythm is increased in extent after the removal of tonic inhibitory impulses. The normal effect of stimulation of the sympathetic nerve supply to the muscular coat of the gallbladder, whether by electrical excitation of the right splanchnic or by intravenous injection of adrenalin, is relaxation. The apparently motor effects first described by Doyon are in all

The Associated Movements of the Eyes their Nerve Centres, Conducting Paths, Production, Varieties and Derangements

The general relations of the associated ocular movements to the nerve tracts and centres concerned in producing them are here considered under these principal divisions: The supranuclear apparatus and the movements it produces. Association centres in cerebral cortex and movements with which they are concerned. The association pathways connected with the cerebellum and labyrinth. The descending paths connecting the centers with the nuclei. The functions of the centers as to origin and varieties of movements produced. The role of inhibitory impulses in regard to associated movements is taken up. Unicentral and bicentral movements, varieties of associated paralysis, paralyses that are essentially unilateral and paralysis of bilateral movements are discussed.

STEREOTROPISM AS A FUNCTION OF NEUROMUSCULAR ORGANIZATION

From what has been said concerning the neuromuscular organization of the Asterias ray, it is possible to arrive at certain definite conclusions regarding the nature of the stereotropism of that organ. The righting movements from the start are not haphazard; i.e., they cannot be explained on any hypothesis of "trial and error." The excitation of the sensory cells of the dorsal sheath initiates dorsal flexure of the ray. This movement makes it possible for the tube feet of the tip to touch bottom and start the vigorous action which follows and completes the righting If the "feelers" by chance touch bottom they initiate the reaction de novo. As to the remaining phases, the stereotropic reaction of the ray is referable to the high degree of surface sensitivity of the tube feet disks and the propagation of excitatory and inhibitory impulses, resulting from stimulation, along appropriate paths to the muscles of the ray. In this respect the tube feet may be regarded as playing a role similar to that of tropistic receptors in general. That is, unequal stimulation of the receptors causes a corresponding inequality of tone or of contraction in the musculature which ultimately results in an equilibrium of orientation to the factor involved. It is evident that as a mechanism for righting stereotropism differs in one important respect from other tropisms. The latter depend for their operation upon unilateral effects in organisms which are dynamically bilaterally symmetrical. In stereotropism the sensitivity of the organism is not distributed in bilaterally symmetrical fashion. As a rule only the ventral side is stereosensitive; i.e., the sensitivity is unilaterally distributed. There is a tropistic action in such cases because of the fact that when the sensitive surface is only partially stimulated an unequal contraction of the musculature follows and this as a result brings the sensitive surface into such a position that it is all equally stimulated. Equal muscle tone follows and the organism is in equilibrium with its environment.

The innervation of the gall-bladder

There are at present two theories as to the innervation of the gall-bladder. One is that supported by Doyon, who claims that the motor fibers pass through the splanchnics; the other theory, which is defended by Dale and Bainbridge, assumes that the motor fibers are derived from the vagi and that the splanchnics carry inhibitory impulses to the gall-bladder.It seemed that this problem could be definitely solved by a study of the isolated gall-bladder. Although it is impossible in such an experiment to excite the nerves directly by the electric current, the same end result may be brought about by the employment of drugs.The effects of those drugs which stimulate the para-sympathetic system may be regarded as analogous to the effects following electrical excitation of the vagus. Epinephrine produces the same effect as electrical stimulation of the splanchnic nerves.The experiments have demonstrated without question that both physostigmine and pilocarpine stimulate the gall-bladder to contract; that atropine ...

The Feigning of Death

THE discussion, a few months since, of the feigning of death in reptiles (vols. li. pp. 107, 128, 223, and lii. p. 148), induced me to experiment on the Currant Moth, whose powers of “shamming” are so familiar. The moth was first seized by one wing, and it at once feigned death; thereupon I cut off its head with a pair of scissors, and the animal continued to feign death. I use the expression advisedly, for absolute immobility was maintained for some seconds, and then violent fluttering ensued, causing the animal to rush wildly about the table, but failing to lift it into the air. In this condition any impulse, such as touching or pinching, induced a repetition of “shamming.” After a strong stimulus the shamming was prolonged, and indeed a direct connection was obvious between the strength of stimulus and the length of period of quiescence. This power of response to stimulus was maintained for two days, and then weak fluttering set in for some hours, followed by death. Our entire ignorance of the physiology of the nervous system of insects renders it difficult to draw complete conclusions from these phenomena; nevertheless, it is difficult to conceive that volition can persist for forty-eight hours in a decapitated animal. We are forced then to conclude that here, at any rate, death-feigning is a purely reflex phenomenon, and that the sensory stimulus received by the surface of the body causes inhibitory impulses to arise reflexly from the ganglia of the central nerve chain, and prevent all movement of the locomotor muscles. In confirmation of this, it may be mentioned that denuding the wing of its scales over any area caused a marked diminution of sensitiveness over the area so treated. Since all stages between sensory hairs and ordinary scales occur in Lepidoptera, it is not unreasonable to assume that the scales still function as tactile end-organs, in spite of their modification subserving decorative purposes.