| Mouth |
- Ingests food
- Chews and mixes food
- Begins chemical breakdown of carbohydrates
- Moves food into the pharynx
- Begins breakdown of lipids via lingual lipase
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- Moistens and dissolves food, allowing you to taste it
- Cleans and lubricates the teeth and oral cavity
- Has some antimicrobial activity
|
| Pharynx |
- Propels food from the oral cavity to the esophagus
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- Lubricates food and passageways
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| Esophagus |
- Propels food to the stomach
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- Lubricates food and passageways
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| Stomach |
- Mixes and churns food with gastric juices to form chyme
- Begins chemical breakdown of proteins
- Releases food into the duodenum as chyme
- Absorbs some fat-soluble substances (for example, alcohol, aspirin)
- Possesses antimicrobial functions
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- Stimulates protein-digesting enzymes
- Secretes intrinsic factor required for vitamin B12 absorption in small intestine
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| Small intestine |
- 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
- Performs physical digestion via segmentation
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- Provides optimal medium for enzymatic activity
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| 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
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- Bicarbonate-rich pancreatic juices help neutralize acidic chyme and provide optimal environment for enzymatic activity
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| Large intestine |
- Further breaks down food residues
- Absorbs most residual water, electrolytes, and vitamins produced by enteric bacteria
- Propels feces toward rectum
- Eliminates feces
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- ·Food residue is concentrated and temporarily stored prior to defecation
- Mucus eases passage of feces through colon
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