Function of Stomach

1. Storage function

As food enters the stomach, it forms concentric rings in the body and fundus of the stomach, the newest food lying close to the esophageal opening while the already reserved food moving towards the wall of the stomach. When food enters the stomach, the vagal tone decreases the muscular tone of the stomach so the wall can bulge outwards to accommodate a greater quantity of food (1.5L).


2. Mixing/shuffling and propulsion of food in the stomach

The gastric glands of the stomach secrete digestive juices these secretions come immediately in contact with the food in the stomach. When the stomach is filled with food weak peristaltic waves (missing waves) move towards the antrum of the stomach along the stomach wall. These mixing waves are initiated by the basic electrical rhythm (BER) produced once every 20 seconds. These waves move down the stomach and not only cause the mixing of secretions with food (semi-digested food). But also provide weak propulsion to move the food towards the antrum.


3. Emptying of the stomach

Gastric emptying occurs when the food is broken down into pieces small enough to pass through the pyloric sphincter. Each time the chyme is pushed again the pyloric sphincter, a small amount (2.7) ml escapes into the duodenum. The amount of chyme passing through the pylorus relies on the size of the particles. If the particles are large no chyme can pass into the duodenum. It can be observed that The rate of gastric emptying of the solid particles depends upon the rate. Which is broken down into small particles. Gastric emptying is regulated by signals from the stomach and duodenum, these are:

  1. Nervous signals caused by distention of the stomach by food.
  2. Gastric (hormone) secreted from the antral mucosa in response to certain types of food.

Both of these factors promote gastric emptying.


4. Secretion

The stomach secretes gastric juices which act as a digestive fluid.


5. Antiseptic function

The parietal or oxyntic cells of the stomach secrete HCI which acts as an antiseptic against swallowed bacteria.


6. Digestion

In the presence of gastric juices, the stomach digests proteins into peptones. It also digests fats to some extent with the help of gastric lipase. Gastric rennin coagulates the milk, while HCI causes some hydrolysis of foodstuff.


7. Absorption

Water, glucose, alcohol. and certain drugs are absorbed from the stomach; the parietal cells secrete intrinsic factor which is necessary for the absorption of vitamin B₁₂.


8. Excretion

The stomach excretes certain toxins e.g. urea and certain alkaloids e.g. morphine.