Function of the Stomach

The human stomach is located on the upper left region of the abdominal cavity and is a vital part of the digestive system. It lies just beneath the diaphragm and is muscular and hollow in nature. If you take a look at the alimentary canal, stomach is preceded by the esophagus and followed by duodenum. In other words, this part of the digestive system is placed between the esophagus and the duodenum. The esophageal sphincter controls the movement of food from the esophagus to the stomach and the pyloric sphincter is responsible for regulating the motion of partially digested food from the stomach to the duodenum, which is the first part of the small intestine.

Stomach Structure

If you take a look at the various organs that form the alimentary canal, the stomach is the most dilated one. Apart from being dilated, it is also expandable. It is a sac-like structure with an empty volume of around 45 to 50 ml (in humans). However, in normal adult humans, it can get enlarged, so as to hold 1 to 3 liters of food. This is not applicable for babies, who can hold only 30 ml in their stomach. In short, the size of the stomach will get altered as per the amount of food inside it. In an average adult, the stomach has a length of around twelve inches and a width of around fifteen inches.

Parts of the Stomach: The stomach has four parts, which are named as cardia, fundus, corpus (body), antrum and pylorus. While cardia is the first part of the stomach, which receives food from the esophagus, fundus is that section of the stomach, that is formed by the greater curvature. The body of corpus forms the main central region of the organ and the pylorus along with the antrum forms the last part that empties the contents of the stomach to the duodenum.

Layers of Stomach Wall: The innermost layer of the stomach wall is called mucosa and the stomach acids are produced and secreted in this layer. The next layer is submucosa, which is made of connective tissues. This layer is covered by muscularis externa and then serosa. Muscularis externa consists of three layers of muscles, that are responsible for mixing the food with enzymes and the movement of the food. So, this layer has an important role in the function of the stomach. The outermost layer is serosa, which is made of connective tissues.

Stomach Secretions: The inner surface of the stomach has different types of epithelial cells that produce various secretions which aid the process of digestion. This includes mucus cells that produce mucus, which is alkaline in nature. This mucus prevents harm to the inner layer of the stomach from acids. There are chief cells that produce an enzyme called pepsin (aids in the stomach function of breaking down proteins) and parietal cells that produce hydrochloric acid (fights microorganisms and digests food). Another type of epithelial cells in the stomach are G cells that produce a hormone called gastrin. The inner surface of the stomach has several foldings that are termed as rugae, which flatten as the stomach expands.

What is the Function of the Stomach

Now, you have a basic idea about the structure of the stomach and the functions of these parts. It is a coordinated effort of these parts that constitute the stomach function. We all know that the primary function is collection and breaking down of food. Let us take a look at how this happens. The food we eat is chewed in the mouth, and it is said that the process of digestion starts in the mouth. What happens in the stomach can be considered as a second phase of digestion. The chewed food reaches the stomach and gets mixed with the acids and enzymes produced in the organ. This mixture is called chyme, which is stored in the stomach and is released to the small intestine in smaller amounts. Thereafter, it is the small intestine's function to further break down the chyme and absorb the nutrients. So, the primary function of the stomach is the breaking down of the food and mixing it with digestive acids and enzymes. Apart from that, the secretions of the stomach kills harmful microorganisms like some bacteria.

In short, stomach's function is to aid digestion by breaking down the food and mixing it with acids and enzymes, thereby releasing the resultant chyme to the small intestine.