Stomach
Stomach is part of the digestive system and receives food from the esophagus. A bottle shaped organ in humans. It is normally less than 20 cm (18 in) long and weighs about 1 percent of the body weight. It is capable, however, of distending greatly to accommodate large meals without increasing the pressure to tension on its walls. The stomach secretes large amounts of hydrochloric acid, which digests protein, activates pepsinogen to form the enzyme pepsin, and kills bacteria that enter the stomach. Acid is secreted from the oxyntic gland area of the gastric mucosa; other cells in this area secrete mucus and the proenzyme pepsinogen. Mucosa lubricates and protects the stomach wall and prevents acid from digesting the stomach itself. Pepsin is an enzyme that aids in the digestion of protein . The mucosa of the distal third of the stomach (antrum) produces and releases the hormone gastrin into the bloodstream), which stimulates acid secretion and the growth of mucosa in the digestiv...