Structure and Function of the Digestive System



The digestive system breaks down food into nutrients that can be absorbed and used to generate cellular energy and build body structures. The digestive system includes the alimentary canal (also known as the digestive tract), salivary glands, liver, gallbladder, and pancreas. The alimentary canal is the muscular tube that runs from the mouth, where food is ingested, to the anus, where feces is expelled. The organs that make up the alimentary canal are the mouth, pharynx, esophagus, stomach, small intestine, and large intestine. Each component of the alimentary canal has specialized structures and regions that facilitate nutrient breakdown, transport, and absorption. The salivary glands and the pancreas synthesize and release most of the digestive enzymes into the alimentary canal, and the liver and gallbladder are important for the digestion of fats.

At A Glance

  • Organs of the digestive system are specialized to facilitate nutrient breakdown, transport, and absorption.
  • Food moves through the alimentary canal via peristalsis and segmentation and moves from one organ to another through sphincters.
  • Food is ingested and partially digested in the mouth before passing through the pharynx and esophagus during swallowing.
  • The stomach stores food and mixes it with acidic secretions to produce chyme.
  • The small intestine and associated accessory organs such as the liver, gallbladder, and pancreas are primarily responsible for chemical digestion of foods and for absorption of nutrients and electrolytes.
  • The large intestine is primarily responsible for absorbing water from undigested materials coming from the small intestine and eliminating the waste as feces.