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Overview of the Male Reproductive System

Author(s): Roberta Anding, MS, RD/LD, CDE
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Human Digestive System Diagram

The digestive system includes the gastrointestinal tract (mouth, pharynx, esophagus, stomach, small and large intestines) along with accessory structures (teeth, tongue, salivary glands, liver, gall bladder and pancreas). Food materials are broken down to usable nutrients and absorbed into the bloodstream. They are used by the body for metabolism, building and repair. Some nutrients are stored within the body. 

The lining of the small intestine consists of tiny folds, called villi, which, in turn, are covered by microvilli. Microvilli have brush border enzymes to hydrolyze lactose and sucrose. The villi contain capillaries and lymphatic vessels for the absorption of nutrients.