GIkanalens

GIkanalens, or the gastrointestinal canal, is the continuous tube through which food passes from the mouth to the anus. It is responsible for digestion, absorption of nutrients, and water balance, and it serves as a barrier against pathogens. In medical contexts, GIkanalens encompasses the gastrointestinal tract, including the upper tract (mouth, pharynx, esophagus, stomach) and the lower tract (small and large intestines).

The upper GI tract begins at the oral cavity and ends at the pylorus of the stomach; the lower GI tract includes the small intestine—duodenum, jejunum, ileum—and the colon, rectum, and anal canal. Accessory organs such as the liver, pancreas, and gallbladder secrete bile and enzymes into the GIkanalens to aid digestion.

Digestive processes include mechanical breakdown, chemical digestion by enzymes, acid and bile, and absorption of nutrients and water. Absorption primarily occurs in the small intestine, with significant water reabsorption in the colon. Motility is regulated by smooth muscle, neural reflexes in the enteric nervous system, and hormonal signaling, which coordinate transit, secretion, and digestion.

The wall of the GIkanalens consists of four layers: mucosa, submucosa, muscularis externa (circular and longitudinal muscle), and serosa or adventitia. The enteric nervous system comprises the myenteric and submucosal plexuses, coordinating motility and secretion with modulation from the autonomic nervous system.

The gut hosts diverse microbiota that influence digestion and immunity. Clinically, GIkanalens disorders include gastroesophageal reflux disease, peptic ulcers, inflammatory bowel disease, irritable bowel syndrome, infections, and colorectal cancer. Diagnostic methods include endoscopy, imaging, and laboratory tests.