Gut

Structure

The gut is roughly nine meters long in total, lined throughout by epithelium and surrounded by smooth muscle. Most absorption occurs in the small intestine, while water reclamation and waste storage happen in the large intestine.

Function

Peristaltic waves of the muscle move contents forward, while specialized cells secrete enzymes, mucus, and hormones that coordinate digestion. A dense network of neurons sometimes called the enteric nervous system controls these reflexes locally.

Microbiome

The gut hosts trillions of bacteria that help with digestion, vitamin synthesis, and immune training.