Small Intestine Information

Small Intestine - the longest part of the digestive tract. It is between the preceding stomach and followed by the large intestine. Vast majority of digestion and absorption of food takes place in the small intestine.

Small Intestine Has 3 Parts

The small intestine makes up more than 70% of the length and 90% of the surface area of the gastrointestinal tract and is made of 3 sections:

• Duodenum
• Jejunum
• Ileum

Absorption of Nutrients

Food from the stomach is allowed into the duodenum, and is pushed through the small intestine by a process of wavelike contractions called by the surrounding muscles.

The small intestine is where most chemical digestion takes place. Most of the digestive enzymes that act in the small intestine are secreted by the pancreas and enter the small intestine.

The three major classes of nutrients that undergo digestion are proteins, lipids (fats) and carbohydrates:

• Proteins
• Lipids (fats)
• Carbohydrates
• Iron is absorbed in the duodenum
• Vitamin B12 is absorbed in the ileum
• Water and lipids are absorbed by passive diffusion throughout the small intestine
• Sodium is absorbed by active transport and glucose and amino acid co-transport
• Fructose is absorbed by facilitated diffusion.

Cancers of the Small Intestine

The most common cancerous (malignant) tumors of the small bowel include

• Adenocarcinoma
• Lymphoma
• Sarcoma
• Carcinoids

In industrialized countries, adenocarcinoma occur most often while in developing countries, lymphomas are much more common. All these tumors have the potential to invade the bowel wall, spread into adjoining lymph nodes, and move to distant organs (metastasize).

Small Intestine and Defecation

Since most of the digestion and absorption of food takes place in the small intestine, monitoring defecation can show early warning signs in case of problems occurring in the organ. Keep an eye on the shape, color, and consistency of your stools for signs of something unusual happening in the small intestine, digestive tract, or the entire body for that matter.