Clifford J. Barborka

The closing mechanism at the gastroesophageal junction

T HE nature of the closing mechanism at the gastroesophageal junction has been a matter of dispute since the eighteenth century [7]. Controversy exists concerning both the experimental observations and their interpretation. Even such apparently simple points as the presence or absence of an anatomic sphincter, or of a flap valve at the gastroesophageal junction, or the presence or absence of a pinchcock action of the diaphragm has been confirmed by some and denied by others. There is general agreement that a closing mechanism must exist. This is immediately apparent from an appreciation of the fact that there is a negative pleuroperitoneal and esophagogastric pressure gradient. The intraluminal pressure of the stomach is from 10 to 25 mm. Hg higher than in the esophagus on inspiration, and on maximal inspiratory effort against the closed glottis, the pressure differential may rise to as high as 80 mm. Hg [2,3]. If there were no mechanism to close the lumen between these two cavities, reflux of gastric contents into the esophagus would result whenever favored by gravity. A sphincter at the cardia was described by Helvetius 141 in 1719. Contraction and relaxation of this sphincter could account for the unidirectional passage of food and fluids from the esophagus into the stomach and would, at the same time, constitute a barrier against gastroesophageal reflux. Subsequent studies, however, revealed that there was little documented evidence in support of an anatomic sphincter and other explanations were sought. The oblique entrance of the esophagus into the stomach combined with the sharp angle formed by the left wall of the abdominal esophagus and the right side of the gastric fundus were considered to constitute a flap valve which permitted the easy passage of food and liquids into the stomach. This valve was considered capable of preventing reflux [5,6]. A valve-like mechanism was also postulated based upon the behavior of the gastric mucous membrane. The mucosal folds about the cardiac orifice have the aspect of a rosette which could assist in preventing retrograde flow into the esophagus [7]. Extrinsic factors have also been considered to have an essential role in the closing mechanism. The diaphragm, the diaphragmatic-esophageal membrane, and the liver tunnel could help maintain the normal anatomic relationships which are necessary for normal functioning of the closing mechanism. It has been suggested that the bundles of muscle surrounding the diaphragmatic hiatus participate activeiy by pinching the esophagus shut by lateral compression, the so-called “pinchcock” action [S]. Finally, more recent physiologic studies have led to the concept

Effect of a Carbonic Anhydrase Inhibitor, Acetazoleamide, Upon Gastric Secretion in Man: Report of its Use Separately and in Conjunction with Anticholinergic Drugs

Summary 1.Diamox in dosage of 1 gram per 24 hours exerts a significant inhibitory effect upon gastric hydrochloric acid production without influencing the volume of gastric secretion. 2.Inhibitory effects on gastric hydrochloric acid were noted with ProBanthine, 15 mg. four times a day, and with Pathilon, 25 mg. and 50 mg. four times a day. 3.Statistically significant conclusions cannot be drawn from the preliminary observations on Diamox in combination with anticholinergic drugs. 4.These studies support the concept that carbonic anhydrase in the parietal cell has an important role in the process of acid secretion of the stomach.

FURTHER OBSERVATIONS ON THE MECHANISM OF ULCER PAIN

Excerpt Direct chemical irritation by hydrochloric acid and disordered motor activity of the stomach and duodenum have been implicated in the causation of ulcer pain. The presence or absence of vas...

Diverticulosis and diverticulitis.

Summary Diverticulosis without inflammatory changes is a benign condition requiring no particular treatment of itself. It is best managed by medical measures directed at preventing diverticulitis, of which it is the necessary precursor. Diverticulitis per se almost always should be treated conservatively. Nearly three quarters of all the patients will respond to medical treatment. Surgical intervention is reserved for the management of complications. Complicated diverticulitis, however, of either the acute or the recurrent type, remains a difficult therapeutic problem.