Gastric emptying involves storage of ingesta, mixing with gastric secretions, grinding of solid food into particles that are 1 to 2 mm in diameter, and the delivery of chyme into the small intestine at a rate designed to optimize digestion and absorption. Knowledge of the mechanical factors by which the stomach moves its contents into the small intestine is limited. This situation reflects, at least in part, the technical difficulties associated with the investigation of human gastric motility. An optimal strategy to evaluate gastric mechanics dictates that a number of factors be measured simultaneously, such as gastric muscular contractions in different regions of the stomach and proximal small intestine, gastroduodenal pressure gradients and transpy-loric flow. There are fundamental differences in the potential impact on luminal flow of contractions that result in occlusion of the lumen and those that do not; hence both lumen-occlusive and nonlumen-occlusive contractions should be quantified. It is recognized that the spa-tiotemporal organization of muscular activity, not just contractile force, is an important determinant of the movement of luminal content. Accordingly, many research studies use a combination of methods. Buy drugs with confidence – buy yasmin online to see how cheap your treatment can be.
Cannon and Lieb, in 1911, observed that transpy-loric flow in animals is predominantly pulsatile rather than continuous. Thus, most liquefied chyme is propelled into the duodenum as a series of small gushes. The characteristics of individual flow pulses (both duration and volume) vary considerably, so that forward, interrupted and reverse flow may all occur. Contrary to the previous suggestion that one motor region could exert the dominant role, the major determinant of patterns of transpyloric flow appears to be the integration of motor activity in the proximal stomach, antrum, pylorus and proximal small intestine.