Sophisticated Stomachs

Pig stomach.

Pig stomach (photo credit) pigsite.com

This week I will be writing about the pig stomach. It is very different from the cow and horse stomach, being an omnivore’s stomach. The pig stomach has four distinct areas called the Esophageal region, the pyloric region, the fundic region, and the cardiac region. The esophageal region is located at the entrance of the stomach, connecting it to the esophagus. This region of the stomach does not secrete digestive enzymes, but has significance in that this is where ulcer formation in pigs occurs. Irritation in this area due to fine particle size, stress or other environmental factors can contribute to ulcer formation in swine. Once food passes through this region, it enters the cardiac region. In the cardiac portion of the stomach, mucus is secreted and mixed with the digested food. Food then passes into the fundic region, which is the first major portion of the stomach that begins the digestive process. In this region, gastric glands secrete hydrochloric acid, resulting in a low pH of 1.5 to 2.5. This reduced pH kills bacteria ingested with the feed. Other secretions in this region are present in the form of digestive enzymes, specifically pepsinogen. Pepsinogen is then broken down by the hydrochloric acid to form pepsin, which is involved with the breakdown of proteins. Finally the digesta moves to the bottom of the stomach, which is the pyloric region. This region is responsible for secreting mucus to line the digestive membranes to prevent damage from the low pH digesta as it passes to the small intestine. The pyloric sphincter regulates the amount of chyme (digesta) that passes into the small intestine. This is an important function so as not to overload the small intestine with chyme so proper and efficient digestion and absorption of nutrients occurs. In addition, once the chyme leaves the stomach, the material is quite fluid in consistency. As you probably know, pigs are notorious for eating anything and everything. So their stomachs must be able to digest a vast variety of foods and non-food items. Conclusively, the stomach is a very sophisticated organ that shows great design, and if it was just slightly off, the animal could die.