Suoliston

Suoliston, the intestine, is the organ within the digestive system responsible for nutrient absorption, water reabsorption, and waste elimination. In Finnish usage, suolisto denotes the whole intestinal tract, while suoliston is the genitive form (for example, the walls of the intestine). The tract is divided into the small intestine and the large intestine, each with distinct parts and roles.

Anatomy and structure: The small intestine comprises the duodenum, jejunum, and ileum, where most chemical digestion and nutrient absorption occur. The large intestine, or colon, absorbs water and electrolytes and forms solid waste; the final segment is the rectum. The intestinal wall features a mucosa with villi and microvilli that increase surface area, a submucosa, and muscular layers that coordinate peristalsis and segmentation. The ileocecal valve regulates flow from the ileum to the large intestine.

Function and microbiota: In the small intestine enzymes from the pancreas and bile finish digestion, and most nutrients are absorbed in the upper sections. The large intestine hosts a diverse microbiota that ferments indigestible carbohydrates, producing short-chain fatty acids used by colonocytes, and contributes to immune function and barrier integrity.

Clinical relevance: The intestine is involved in a range of conditions, including inflammatory bowel disease, celiac disease, infections, malabsorption, and colorectal cancer. Management depends on the condition and may involve diet, medications, or surgery, with attention to maintaining gut microbiota health and nutrient balance.