The J-shaped curved fleshy sac located below the diaphragm and above the abdomen is called the stomach. Its wall is very thick and muscular. Its length is 30.5 cm and width is about 15.2 cm. Stomach consists of five parts. Cardiac stomach, fundus, body, antrum and pyloric stomach.
(i) Cardiac Stomach: The part of the stomach where the esophagus opens is called the cardiac stomach. At the junction of the esophagus and the cardiac stomach is a muscular ring called the cardiac sphincter. The ring of muscles prevents food from entering the esophagus.
(ii) Fundus: The convex part on the left side near the cardiac stomach is called fundus.
(iii) Body: The central region of the stomach posterior to the fundus is called the corpus. It contains food.
(iv) Antrum : The posterior part of the corpus is called antrum. Food is temporarily stored in the antrum before entering the intestine.
(v) Pyloric Stomach: The part of the stomach which opens into the duodenum is called pyloric stomach. At the junction of the duodenum and the pyloric stomach is a muscular ring called the pyloric sphincter. The musculature helps the food to enter the duodenum.
Stomach function
(i) Digested, fatty and partially digested food stays in the stomach for 2-24 hours. Cardiac sphincter prevents retrograde flow of food.
(ii) Oeish released from parietal cells destroys microbes, dissolves mineral salts, decalcifies bones and creates an acidic environment.
(iii) Peristalsis is the process of movement of food in the stomach after 15-20 seconds.
(iv) Food is crushed into a soft paste.
(v) Digestive juices and paste mix to form slimy mucus or chyme.