While the reference lists 6 activities, a complete view identifies 7 key functions of the digestive system:
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Ingestion: The process of taking food into the digestive system, typically through the mouth. This is the first step in processing food.
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Propulsion: The movement of food through the digestive tract. This involves swallowing (voluntary) and peristalsis (involuntary waves of muscle contraction).
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Mechanical Digestion: The physical breakdown of food into smaller pieces. This increases the surface area for chemical digestion. Examples include chewing, churning in the stomach, and segmentation in the small intestine.
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Chemical Digestion: The enzymatic breakdown of food into simpler molecules that can be absorbed. This involves enzymes secreted by various digestive organs, breaking down carbohydrates, proteins, and fats.
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Secretion: The release of enzymes, hormones, and other substances that aid in digestion. This includes the secretion of gastric juice in the stomach, bile from the liver, and pancreatic enzymes from the pancreas.
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Absorption: The movement of digested nutrients from the digestive tract into the blood or lymph. This primarily occurs in the small intestine, where nutrients are absorbed into the bloodstream for distribution throughout the body.
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Defecation (Elimination): The removal of indigestible wastes and bacteria from the body in the form of feces. This is the final step in the digestive process.
