Small Intestine

Small Intestine

The small intestine is a vital organ in the digestive system of humans and many other animals. It is responsible for the absorption of nutrients and minerals from food. Structurally, the small intestine is a tubular segment of the gastrointestinal tract that follows the stomach and precedes the large intestine. It is divided into three parts: the duodenum, the jejunum, and the ileum.

Anatomy

The small intestine is approximately 20 feet (6 meters) long in adults, though its length can vary. It is coiled and occupies a central position in the abdominal cavity. The duodenum is the shortest section, forming a C-shaped curve around the head of the pancreas. It receives partially digested food (known as chyme) from the stomach, along with bile from the gallbladder and digestive enzymes from the pancreas, which aid in the digestion process. The jejunum and ileum, which make up the remainder of the small intestine, are primarily involved in the absorption of nutrients and minerals.

Function

The primary function of the small intestine is the digestion and absorption of nutrients. The inner surface of the small intestine is lined with millions of microscopic, finger-like projections called villi, which increase the surface area for absorption. Each villus contains blood vessels and a lymphatic vessel (lacteal) that help transport absorbed nutrients. Digestive enzymes from the pancreas and bile from the gallbladder continue to break down food as it moves through the small intestine, allowing for the absorption of vitamins, minerals, proteins, fats, and carbohydrates.

Clinical Significance

Several conditions can affect the small intestine, including Celiac disease, Crohn's disease, and small intestinal bacterial overgrowth (SIBO). These conditions can lead to symptoms such as abdominal pain, bloating, and diarrhea, and may require medical intervention for management.

See Also

• Digestive system
• Gastrointestinal tract
• Human anatomy