Short answers, pulled from the story.
The small intestine is a 20-foot-long tube that is actually longer than the large intestine. It fits entirely within the abdomen despite stretching from the chest to the knees if laid out straight.
The small intestine is divided into the duodenum, jejunum, and ileum. The duodenum neutralizes acid, the jejunum absorbs sugars and amino acids, and the ileum absorbs vitamin B12 and bile salts.
The small intestine begins its development in the fifth week of embryological life when the midgut of the primitive gut tube starts to grow rapidly. By the tenth week, the loop retracts back into the abdomen after rotating 180 degrees anticlockwise.
The small intestine lies in a complex arrangement between the stomach and the colon. It receives digestive juices from the pancreas and bile from the liver to break down food into usable components.
The small intestine has a surface area roughly the size of a tennis court due to circular folds, villi, and microvilli. These microscopic structures maximize the surface area for nutrient uptake and allow for incredible speed and efficiency in absorption.