This PowerPoint presentation discusses the small intestine. It notes that the small intestine is one of the most important organs for immune defense and is the largest endocrine organ. The small intestine starts at the pylorus and ends at the cecum. It is divided into three parts: the duodenum, jejunum, and ileum. The duodenum contains Brunner's glands which secrete an alkaline fluid to neutralize stomach acid. The jejunum and ileum absorb nutrients from digested food. The small intestine plays a key role in digestion and absorption of nutrients.