Stomach is a muscular organ of our body located on the left and upper side of the abdomen. It is a part of the digestive system and the storage house of the food that we consume.
The Stomach of an adult man has an average length of 30 centimetres and width of 15 centimetres. A healthy Stomach can stretch expanding itself to hold food of nearly 1 litre.
The Stomach can be divided into five parts. They are as follows:
Cardia: It is the upper portion of the Stomach where the oesophagus (food pipe) joins the Stomach. It has a ring of muscle known as the cardiac sphincter. It acts like a valve and prevents the food from going back to the oesophagus.
Fundus: It is the inner side of heart that follows the cardia and is raised physiologically above the cardia. It also acts as a temporary food storage area.
Body of Stomach: Below the fundus is the biggest part of the Stomach which is known as the body of the Stomach. It is that part where the main mixing and breaking down of food happens.
Antrum: It is the lower part of the Stomach that forms its base where the broken foods are held until it’s time to be released into the small intestine.
Pylorus: It is the end of Stomach, after which starts the small intestine. It is a narrow valve that consists of a ring of muscle known as pyloric sphincter which controls emptying of food from Stomach to small intestine.
The wall of Stomach is a set of several layers of tissue which protects and serves different functions for the Stomach. The layers are as follows:
Mucosa: It is the innermost layer which produces mucus, a slimy substance, to protect the wall from the acids produced in the Stomach for digestion, hydrochloric acid and digestive enzymes.
Submucosa: It is the layer next to mucosa and it is made up of connective tissues, blood vessels, nerve cells and fibres and digestive hormones producing glands.
Muscularis propria: It is the muscular layer of the Stomach whose main function is to mix and smash the food with the help of its muscular contraction.
Serosa: It is the outermost layer of Stomach and also forms its cover. This layer is fibrous in nature.
The main function of the Stomach is to store the food so that we avoid eating continuously so as to meet the requirement of energy in our daily lives. It helps in the digestion of food as well. The muscles of the muscularis propria mixes the food, acids and enzymes produced by the glands of mucosa and break the food down into semi-liquid substance known as chime which is later passed down the small intestine through the pyloric sphincter. It also helps in destroying the contaminants such as bacteria, which are in the food.
Stomach produces a lot of substances that control and enhance the process of digestion. The most important is the gastric juice which is a mixture of mucus, hydrochloric acid and digestive enzymes. There is also a type of cells known as parietal cells which secretes hydrochloric acid and intrinsic factor which is a glycoprotein (a protein with carbohydrate as its non-protein component). This glycoprotein binds with Vitamin B12 in the food and helps it absorb in the small intestine. Another type of cells known as Chief cells produces two digestive enzymes – pepsinogen (precursor of protein-digesting enzyme, pepsin) and gastric lipase (fat digesting enzyme). The G-cells of the Stomach produces a hormone known as gastrin, which increases the secretion of gastric juice.
The major disorders of Stomach are:
Gastritis: Here, the inner linings of the Stomach are swollen or eroded.
Stomach cancer: It is also known as gastric cancer and the cancer grows from the inner lining of the Stomach.
Gastroparesis: It is a condition in which our Stomach takes longer time to empty the food that has been stored in it.
Gastritis is mainly caused due to excessive consumption of alcohol, chronic vomiting or use of anti-inflammatory drugs. The symptoms are nausea, abdominal pain, vomiting, indigestion etc. The main cause of Stomach cancer is heredity and its symptoms are indigestion, loss of appetite, mild nausea etc. Gastroparesis is caused due to uncontrolled diabetes, gastric surgery etc. Nausea, vomiting undigested food, poor appetite and blood sugar control etc. are some of its symptoms.