Why is a small intestine shaped like it is?

The small intestine is shaped like a long, coiled tube because it needs to maximize its surface area for nutrient absorption. The inner lining of the small intestine is covered in tiny, finger-like projections called villi, and each villus is covered in even smaller microvilli. These villi and microvilli increase the surface area of the small intestine by many folds, allowing it to absorb nutrients from food more efficiently.

In addition, the small intestine is coiled to allow it to fit into the limited space of the abdominal cavity. The coils also help to mix food with digestive juices and move it along the length of the intestine.

Finally, the shape of the small intestine helps to slow down the passage of food, allowing more time for nutrients to be absorbed.