How are mammals’ digestive tracts different from other animals?
Unlike some other animals, all mammals begin their digestive process by taking food into their mouth. The tissues in the mouth are protected with layers of keratin so that mechanical digestion can take place. Some chemical digestive fluids are secreted from salivary glands to break down starches. Mammals then use a tongue to propel food to the bolus. Food is propelled down the esophagus into the stomach where chemical and mechanical digestion continue to occur. Gastric pits release enzymes to break down the food. The broken down product moves to the small intestine where the enzymes are neutralized, chemical digestion finishes, and absorption occurs. Circular folds, villi and thin tissues allow mammals to absorb nutrients efficiently. The remaining fluid moves to the large intestine so electrolytes can be absorbed and bacterial digestion can occur. Water used in this process is reclaimed and all waste products move to the colon and is excreted through the anal canal.