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Stomach

Stomach.png

The human stomach, a muscular hollow organ in the upper abdomen, is pivotal in the digestive process, storing and breaking down food while regulating its passage into the small intestine. Anatomically, it is divided into four regions: the cardia (entry point for food), the fundus (storage area for undigested food and gases), the body (central region for major digestion), and the pylorus (regulates food passage into the intestine).

 

The stomach's functions include mechanical digestion through muscular contractions that mix and break down food, and chemical digestion through gastric juices containing hydrochloric acid (HCl), pepsinogen (converted to pepsin to break down proteins), and intrinsic factor (necessary for vitamin B12 absorption). Mucous cells protect the stomach lining with mucus, while G cells produce gastrin to stimulate acid production. Gastric secretion occurs in three phases: the cephalic phase (triggered by the sight, smell, or thought of food), the gastric phase (activated by food entering the stomach), and the intestinal phase (regulating the rate of gastric emptying).

 

The stomach’s activity is controlled by the nervous system and hormones, such as the vagus nerve and gastrin, with additional regulation by the small intestine through hormones like secretin and cholecystokinin (CCK). Pathological conditions affecting the stomach include gastritis, peptic ulcers, gastroesophageal reflux disease (GERD), and stomach cancer, highlighting the importance of understanding and maintaining gastric health.

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