The Defence Mechanisms Peculiar to the Alimentary Tube

THE defence mechanisms peculiar to the alimentary tube itself are very limited. For analytical purposes they may be considered under the already mentioned broad classification of mechanical and chemical types of assault. Mechanical Assault.—The most easily investigated response to a harmful stimulus is a modification of the muscular activity of the wall of the tube. Since the only stimulus capable of evoking visceral pain is stretching leading to an exaggerated muscular activity, visceral pain of […]

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The General Anatomical Disposition of the Abdominal Part of the Alimentary Tube

THE original conception of an arrangement of the various parts of the abdominal alimentary tube within fixed ana- tomical boundaries, was completely disproved when it became possible to obtain radioscopie views of the alimentary tube in the living subject. From these it was apparent that only a few regions of the bowel could be regarded as even relatively fixed; the variations in position of the other parts were extremely marked. The relatively fixed regions are: […]

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The Lining Membrane of the Alimentary Tube

THE most prominent feature of the mucous membrane lining the alimentary tube is the great collection of glands related to it. The majority of these glands are embedded in the membrane. They are small (microscopic) single tubes lined by secretory cells and opening directly on the free surface of the mucous membrane. The material secreted may be of a simple nature as in the mucous glands, but in other glands, e.g., seromucous glands, certain stomach […]

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The Nervous Arrangements of the Alimentary Tube

THE muscles of Compartment I and of the upper part of Com- partment II as far as the junction of the upper and middle thirds of the oesophagus are chiefly striated muscles and are innervated mainly by somatic nerves; the glandular struc- tures of these compartments are, however, associated with the autonomic system. The part of the alimentary tube from the lower two-thirds of the oesophagus to the anal canal is activated almost entirely by involuntary […]

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The Vascular Arrangements of the Alimentary Tube

Arteries.—In Compartments I and II there are no special points of clinical interest in connexion with the arterial arrangements. The arteries are derived from those supplying structures in the vicinity. In the remainder of the alimentary tube, i.e., the abdominal part, the distribution of the arteries is highly specialized. This accords with the observation that when the distribution of the branches o f a large artery is confined to a particular region, that region is […]

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The Muscular Tunic of the Alimentary Tube

THE walls of Compartment I are composed partly of bones and partly of voluntary muscles. The roof is made up of bones (maxillae and palate) which are immovable. The bone (mandible) entering into part of the side walls is hinged at the temporo-mandibular joints and may be moved in various directions. The side walls are completed by muscles acting on the mandible, cheeks, and lips. The floor consists largely of the tongue, with its foundation […]

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The General Structure and Divisions of the Alimentary Tube

THE alimentary tube is a long continuous tube with an inlet at the mouth and an outlet at the anus (Fig. i). From a functional point of view, it is possible to divide it broadly into three segments. The first segment extends from the inlet of the tube to the middle of the duodenum and may be described as preparatory; here the foodstuffs are mechanically and chemically prepared for presentation to the next segment, but […]

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