Question

Describe how food is processed in the stomach. Add a note on the role of helicobactor pylori in peptide ulcers.

Answer 1

Activities of smooth muscles of stomach increase during gastric digestion (when stomach is filled with food) and when the stomach is empty.   
Types of movements in stomach
1. Hunger contractions
2. Receptive relaxation
3.Peristalsis.   
FILLING OF STOMACH
While taking food, it arranges itself in the stomach in different layers. The first eaten food is placed against the greater curvature in the fundus and body of the stomach. The successive layers of food particles lie nearer, the lesser curvature, until the last portion of food eaten lies near the upper end of lesser curvature, adjacent to cardiac sphincter.
The liquid remains near the lesser curvature and flows towards the pyloric end of the stomach along a V-shaped groove. This groove is formed by the smooth muscle and it is called magenstrasse. But, if a large quantity of fluid is taken, it flows around the entire food mass and is distributed over the interior part of stomach, between wall of the stomach and food mass.
EMPTYING OF STOMACH
Gastric emptying is the process by which the chyme from stomach is emptied into intestine. Food that is swallowed enters the stomach and remains there for about 3 hours. During this period, digestion takes place. Partly digested food in stomach becomes the chyme.
Chyme
Chyme is the semisolid mass of partially digested food that is formed in the stomach. It is acidic in nature. Acid chyme is emptied from stomach into the intestine slowly, with the help of peristaltic contractions. It takes about 3 to 4 hours for emptying of the chyme. This slow emptying is necessary to facilitate the final digestion and maximum (about 80%) absorption of the digested food materials from small intestine. Gastric emptying occurs due to the peristaltic waves in the body and pyloric part of the stomach and simultaneous relaxation of pyloric sphincter.

Diminished ability of the gastroduodenal mucosal
barrier to protect against the digestive properties of the
acid–pepsin complex. Factorthat disturb mucosal barrier
include:
Bacterial infection by Helicobacter pylori. At least 75%
patients with peptic ulcer have recently been found to
have chronic infection by H. pylori. The bacterium
releases digestive enzymes that liquefy the barrier, which
allows gastric secretion to digest the epithelial cells lead-
ing to peptic ulceration.