Small intestine

Definition

The small intestine is a long, coiled tube where most digestion and nutrient absorption occurs. It consists of three parts: the duodenum, jejunum, and ileum.

5 Must Know Facts For Your Next Test

1. The small intestine hosts a diverse microbiota that plays a crucial role in digestion and immune function.
2. Digestive enzymes from the pancreas and bile from the liver aid in breaking down food in the small intestine.
3. Most water and nutrients are absorbed in the small intestine, particularly in the jejunum and ileum.
4. The mucosal surface of the small intestine has villi and microvilli to increase surface area for absorption.
5. Pathogens like Salmonella, E. coli, and Giardia can infect the small intestine, leading to conditions such as gastroenteritis.

Review Questions

• What are the three main sections of the small intestine?
• How does the microbiota in the small intestine contribute to its functions?
• Name two pathogens that can infect the small intestine and describe their impact.

Related terms

Duodenum:

The first part of the small intestine immediately beyond the stomach.

Jejunum:

The middle section of the small intestine between duodenum and ileum.

Ileum:

The last part of the small intestine before it joins with the large intestine.