Small intestine

Definition

The small intestine is a long, coiled tube where most of the digestion and absorption of nutrients occurs. It connects the stomach to the large intestine and consists of three sections: the duodenum, jejunum, and ileum.

5 Must Know Facts For Your Next Test

1. The small intestine is approximately 20 feet long in adults.
2. It is divided into three parts: duodenum, jejunum, and ileum.
3. Most enzymatic digestion and nutrient absorption occur in the small intestine.
4. The inner surface is lined with villi and microvilli to increase surface area for absorption.
5. Various enzymes from the pancreas and bile from the liver aid in the digestive process within the small intestine.

Review Questions

• What are the three sections of the small intestine?
• How does the structure of villi and microvilli aid in nutrient absorption?
• Which organs provide enzymes and bile to aid digestion in the small intestine?

Related terms

Duodenum:

The first section of the small intestine immediately following the stomach.

Jejunum:

The middle section of the small intestine where much absorption occurs.

Ileum:

The last section of the small intestine that connects to the large intestine.