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Digestive System Anatomy: Alimentary Canal and Accessory Organs

The function of the digestive system is to break down the foods you eat, release their nutrients, and absorb those nutrients into the body. Although the small intestine is the workhorse of the system, where the majority of digestion occurs, and where most of the released nutrients are absorbed into the blood or lymph, each of the digestive system organs makes a vital contribution to this process (Figure 23 2). As is the case with all body systems, the digestive system does not work in isolation; it functions cooperatively with the other systems of the body.

Figures (8)

Illustration of digestive system
General structure of the gut wall
The general structure of the intestinal wall
The wall of the stomach.
Diagram of human microbiota depicted in various regions of the gastrointestinal tract
Image of the mucosa of the stomach, showing an epithelium (at top, and also facing the elongated cavities) made up of column-shaped cells.
Muscular layers of the stomach wall.

Key Points

  • The third layer of the alimentary canal is the muscularis (also called the muscularis externa).
  • The mouth is the first part of the upper gastrointestinal tract and is equipped with several structures that begin the first processes of digestion.
  • The pharynx is a part of the conducting zone of the respiratory system and also a part of the digestive system.
  • At rest the esophagus is closed at both ends, by the upper and lower esophageal sphincters.
  • The stomach is equipped for its churning function by the addition of a third layer, the oblique muscle.
  • The small intestine is a tubular structure around 6 to 7 m long, that begins at the duodenum, and ends at the ileum.

Terms

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Sources & licensing(4)