Royal Army Medical Corps training pamphlet / War Office.

Date:
1944
Catalogue details

Licence: Public Domain Mark

Credit: Royal Army Medical Corps training pamphlet / War Office. Source: Wellcome Collection.

    52/376 (page 44)
    The liver has three main functions :— (a) It collects and alters food brought from the intestine by the portal vein (para. 53). (b) It secretes bile. This is a greenish-yellow fluid which (i) helps to neutralize the acid food from the stomach; (ii) assists in the absorption of fats; (ili) stimulates the large intestines; and (iv) reduces putrefaction in the bowel. (c) It stores carbohydrate and delivers it into the blood- stream, as required, in the form of sugars—the fuel most easily used by the body. Before entering the intestine some of the bile is stored in the gall-bladder, a small greenish pouch. This is liable to disease, when gall-stones may form inside it. 61. Functions of the pancreas.—The pancreas, which lies behind the stomach, is one of the most important glands in the body. It has two secretions :— (a) An external secretion which is conveyed by a duct to the duodenum. This fluid digests proteins, fats, _ and carbohydrates. (6) An internal secretion which takes no part in digestion but passes directly into the blood-stream and enables the muscles and other tissues to use sugar. If the pancreas is diseased and fails to produce this secretion, sugar accumulates in the blood until it is excreted in the urine. This disease is known as diabetes and it is usually treated by daily injections of a pancreatic extract called insulin. 62. The small intestine.—The small intestine (so called because its bore is narrower than that of the large intestine) is about 22 feet long. It is attached to the back wall of the abdominal cavity by a double layer of membrane called the mesentery (Fig. 22, lower drawing), which allows free movement of the coils of intestine within the cavity, Between the folds of the mesentery pass blood and lymph vessels and nerves. The small intestine is divided into three parts—duodenum, jejunum and ileum. The duodenum is the upper 10—12 inches and is more firmly fixed in position than the other parts. Externally there is no obvious division between the jejunum and ileum ; the former forms roughly two-fifths, and the latter three-fifths, of the small intestine, excluding the duodenum. The intestinal wall contains circular and longitudinal layers of, involuntary muscle fibres. These contract slowly at intervals, producing waves of contraction from the upper towards the lower end of the tube, and thus squeeze the food onwards (peristalsis).