Functions of the Digestive Organs

Functions of the Digestive Organs

Mouth

• Major Functions:

  • Ingests food

  • Chews and mixes food

  • Begins chemical breakdown of carbohydrates

  • Moves food into the pharynx

• Other Functions:

  • Begins breakdown of lipids via lingual lipase

  • Moistens and dissolves food, allowing for taste

  • Cleans and lubricates teeth and oral cavity

  • Possesses some antimicrobial activity

Pharynx

• Major Functions:

  • Propels food from oral cavity to esophagus

• Other Functions:

  • Lubricates food and passageways

Esophagus

• Major Functions:

  • Propels food to the stomach

• Other Functions:

  • Lubricates food and passageways

Stomach

• Major Functions:

  • Mixes and churns food with gastric juices to form chyme

  • Begins chemical breakdown of proteins

  • Releases food into duodenum as chyme

  • Absorbs some fat-soluble substances (e.g., alcohol, aspirin)

• Other Functions:

  • Possesses antimicrobial functions

  • Stimulates protein-digesting enzymes

  • Secretes intrinsic factor required for vitamin B12 absorption in the small intestine

Small Intestine

• Major Functions:

  • Mixes chyme with digestive juices

  • Propels food at a rate slow enough for digestion and absorption

  • Absorbs breakdown products of carbohydrates, proteins, lipids, and nucleic acids, along with vitamins, minerals, and water

• Other Functions:

  • Performs physical digestion via segmentation

  • Provides an optimal medium for enzymatic activity

Accessory Organs

• Liver:

  • Produces bile salts, which emulsify lipids, aiding their digestion and absorption

• Gallbladder:

  • Stores, concentrates, and releases bile

• Pancreas:

  • Produces digestive enzymes and bicarbonate

  • Bicarbonate-rich pancreatic juices help neutralize acidic chyme and provide an optimal environment for enzymatic activity

Large Intestine

• Major Functions:

  • Further breaks down food residues

  • Absorbs most residual water, electrolytes, and vitamins produced by enteric bacteria

  • Propels feces toward rectum

  • Eliminates feces

• Other Functions:

  • Food residue is concentrated and temporarily stored prior to defecation

  • Mucus eases the passage of feces through the colon