Small Intestine

The small intestine is a part of the gastrointestinal tract where the majority of digestion and absorption of nutrients takes place. It is located between the stomach and the large intestine, and is made up of three segments: the duodenum, the jejunum, and the ileum.

Anatomy of the Small Intestine

The small intestine is approximately 20 feet long in adults and is lined with millions of tiny, finger-like projections called villi. These villi increase the surface area of the small intestine, facilitating the absorption of nutrients into the bloodstream.

Functions of the Small Intestine

1. Digestion: The small intestine receives partially digested food from the stomach and continues the process of breaking down carbohydrates, proteins, and fats with the help of enzymes from the pancreas and bile from the liver.
2. Absorption: Most of the nutrients from the digested food, including sugars, amino acids, fatty acids, vitamins, and minerals, are absorbed through the walls of the small intestine and transported to the bloodstream for distribution to the body's cells.

Study Guide

To understand the small intestine, it's important to focus on the following key points:

1. Anatomy: Learn the structure and organization of the small intestine, including the three segments and the role of villi in absorption.
2. Functions: Understand the digestive and absorptive functions of the small intestine, and how it works in collaboration with other digestive organs such as the stomach, pancreas, and liver.
3. Nutrient Absorption: Study the specific nutrients that are absorbed in the small intestine, and the mechanisms involved in their uptake into the bloodstream.
4. Disorders: Explore common disorders of the small intestine, such as celiac disease, Crohn's disease, and intestinal infections, and their impact on digestion and nutrient absorption.