The Creation of God, Jacob Hartmann [e manga reader TXT] 📗
- Author: Jacob Hartmann
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While the stomach contains no food, and is inactive, no gastric fluid is secreted; and mucus, which is either neutral or slightly alkaline, covers its surface. But immediately on the introduction of food into the stomach, the mucous membrane, previously quite pale, becomes slightly turgid and reddened with the influx of a large quantity of blood; the gastric glands commence secreting actively, and an acid fluid is poured out in minute drops, which gradually run together and flow down the walls of the stomach, or soak into the substance introduced. The quantity of this fluid secreted daily has been variously estimated; but the average for a healthy adult has been assumed to range from ten to twenty pints in twenty-four hours.
The specific gravity of gastric juice has been found to differ little from that of water, varying from 1.001 to 1.010, and the amounts of solid present to be very small, viz., about 56 per cent.
The chemical composition of gastric juice is:
On starch gastric juice per se has no effect whatever, nor has healthy gastric juice any effect on grape sugar or cane sugar. On fats gastric juice is powerless.
The essential property of gastric juice is the power of dissolving proteid matters (meats, albumens, nitrogenous substances), and converting them into a substance called peptones. Gastric juice thus readily dissolves coagulated proteids which otherwise are insoluble, or soluble only with difficulty in very strong acids.
Certain conditions are required for the perfection of the process, which are all found in the stomach. The first is a temperature of 100° F. Second, minute division and constant movement favor digestion. Third, the greater the surface presented to the action of the juice, the more rapid the solution.
Neutralization of the juice wholly arrests digestion.
The digestive action of gastric juice on proteids, like that of saliva on starch, is a ferment action; in other words, the solvent action of gastric juice is essentially due to the presence in it of a ferment body called pepsin.
The general effect of digestion of the stomach is the conversion of food into chyme, a substance of various compositions according to the nature of the food, yet always presenting a characteristic thick pultaceous grumous consistence.
The small intestines commence at the pylorus and after many convolutions terminate in the large intestines. They measure on an average about twenty feet in length in the adult. For convenience they have been divided into three parts—the duodenum, which extends from eight to ten inches beyond the pylorus; the jejunum, which occupies two-fifths, and the ilium, which occupies three-fifths, of the rest of the canal.
The mucous membrane, the interior coat, is the most important to the function of digestion. There are permanent folds, shelf-like processes, of the mucous membrane, called valvular conniventes. There are also villi and glands, as the glands of Lieberkühn, of Peyer, and of Bruner. The glands of Lieberkühn are thickly distributed over the whole surface of the large and small intestines. The glands of Peyer are exclusively in the small intestine. They are found in greatest abundance in the lower part of the ileum near to the ileo-cæcal valve. They are met with in two conditions, viz., either scattered singly, in which case they are termed glandulæ solitairæ, or aggregated in groups varying from one to three inches in length and about half an inch in width, chiefly of an oval form, their long axes parallel with that of the intestines. In this state they are named glandulæ agminatæ. The latter are almost always placed opposite the attachment of the mesentery. In structure they are analogous to lymphatics or absorbent glands, and their office is to take up certain materials from the chyle, elaborate them, and subsequently discharge them into the lacteals, with which vessels they appear to be closely connected. Bruner’s glands are confined to the duodenum; they are most abundant and thickly set at the commencement of this portion of the intestines, and are provided with permanent gland ducts.
The villi are confined exclusively to the mucous membrane of the small intestines. They are minute vascular processes, from a quarter of a line to a line and two-thirds in length. There are about fifty to ninety in number to a square line. Each villus consists of a small projection of mucous membrane, and its interior is supported throughout by fine retiform or adenoid tissue. Two or more arteries are distributed to each villus, and from their capillaries, which form a dense network, proceed one or two small veins, which pass out at the base of the villus.
The lacteal vessels enter the base of each villus, and passing up in the middle extend nearly to the top, where it ends commonly by a closed and somewhat dilated extremity. The office of the villi is the absorption of chyle from the completely digested food of the intestines.
The large intestine extends from the termination of the ileum to the anus. It is usually about five to six feet in length, being about one-fifth of the whole length of the intestinal canal. The large intestine is constructed of four coats like those of the stomach and small intestines, namely, the serous, the muscular, the areolar or submucous, and the mucous. It is divided into the ascending colon, transverse and descending colon, and rectum and anus.
The cæcum is a short wide pouch, communicating with the lower end of the small intestines through an opening guarded by the ileo-cæcal valve. The appendix vermiformis is attached to the cæcum. The colon commences at the right groin, ascends to the liver, forms the hepatic flexure, then crosses transversely from right to left to the spleen, forms the splenic flexure, descends to the left groin, forms the sigmoid flexure, passes through the pelvis as the rectum, and terminates at the anus.
The mucous membrane of the large intestines, like that of the small intestines, is lined throughout by columnar epithelium, but unlike it, is quite destitute of villi and is not projected in the form of valvular conniventes.
The peritoneum, or serous membrane of the abdominal cavity, is by far the most extensive and complicated of serous membranes. Like the others, it may be considered to form a shut sac, on the outside of which are placed the viscera, which it covers. The peritoneum forms the mesenteries and omenta for the stomach, small and large intestines, and ligaments for the liver, spleen, uterus, and bladder.
The liver is a very important glandular organ, very constant in the animal series, being found in all the vertebrates, and, in a more or less developed condition, in most invertebrate tribes. It secretes bile, and appears to act upon the blood which is transmitted through it. The liver is the largest gland in the body, and by far the most bulky of the abdominal viscera. It measures from ten to twelve inches transversely from right to left, between six and seven inches from its posterior to its anterior border, and about three and a half inches from above downwards where thickest, which is towards the right and posterior part. The average bulk is about eighty-eight cubic inches. The ordinary weight in the adult is between 50 to 60 ounces, about one-thirtieth of the weight of the whole body. The liver is solid to the feel, and of a dull reddish-brown color, with frequently a dark-purplish tinge along the margin. It has an upper surface smooth and convex, and an under surface which is uneven and concave. The liver is divided into two unequal lobes, a right and a left, and on the under surface of the right lobe are three secondary lobes or lobules, named the lobe of Spigolius, the caudate or tailed lobe, and the square lobe. It has five fissures or fossæ, described as the transverse or portal; the umbilical fissure and the fissure of the ductus venosus, together forming the longitudinal fissure; the fossa of the vena cava, and the fossa of the gall bladder. It is held in position by five ligaments formed by layers of peritoneum.
The liver is situated on the right side of the body under the diaphragm. The convex surface is protected, on the right by the six or seven lower ribs, and in front by the cartilages of the same, and by the ensiform cartilage, the diaphragm of course being interposed.
To the left of the longitudinal fissure the liver is in contact with the pyloric extremity and anterior surface of the stomach, on which it moves freely. When the stomach is quite empty, the left part of this surface of the liver may overlap the cardiac end of that organ. To the right of the longitudinal fissure the liver rests upon the first part of the duodenum and the hepatic flexure of the colon. Farther back it is in contact with the upper part of the right kidney and suprarenal capsule.
The two blood-vessels which supply the liver are the hepatic artery and the vena porta. The hepatic vein conveys the blood away from the liver.
The lymphatics of the liver are large and numerous, forming a deep and a superficial set.
The nerves are derived partly from the cœliac plexus and partly from the pneumogastric nerve, especially from the left pneumogastric.
The excretory apparatus of the liver consists of the hepatic duct, the cystic duct, gall bladder, and common bile duct.
The hepatic duct is formed by the union of a right and left branch, which issue from the bottom of the transverse fissure and unite at a very obtuse angle; it descends to the right, within the gastro-hepatic omentum. Its diameter is nearly two lines, and its length nearly two inches. At its lower end it meets the cystic descending from the gall bladder, and the ducts uniting together at an angle form the common bile duct.
The cystic duct is about one and a half inches in length.
The gall bladder is a pear-shaped membranous sac, three or four inches long, about an inch and a half across its widest part, and capable of containing from 8 to 12 fluid drachms. The gall bladder is attached to the liver. The neck, gradually narrowing, becoming constricted, bends downward, and terminates in the cystic duct.
The common bile duct (ductus communis choledicus), the largest of the ducts, being from two to three lines in width, and nearly three inches long, conveys the bile from the liver and the gall bladder into the duodenum by a common orifice, with the pancreatic duct on its inner surface, about three to four inches below the pylorus.
The liver is an extremely vascular organ, and receives its blood supply from two distinct vessels, the portal vein and the hepatic artery, while the blood is returned from it into the inferior vena cava by the hepatic vein. Its secretion, the bile, is conveyed from it by the hepatic duct, either directly into the intestines, or, when digestion is not going on, into the cystic duct, and thence into the gall bladder, where it accumulates until required. The portal vein, hepatic artery, and hepatic duct branch together throughout the liver, while the hepatic vein and its tributaries run by themselves. At the transverse fissure it is merged into the areolar investment called Glisson’s capsule, which surrounds the portal vein, hepatic artery, and hepatic duct, as they enter at this part, and accompanies them in their branches through the substance of the liver.
The liver is made up of
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