Digestive System Anatomy and Physiology - Nursing Education Resource | Functions, GI Tract Structures, and Clinical Relevance

Digestive System Anatomy and Physiology - Nursing Education Resource | Functions, GI Tract Structures, and Clinical Relevance Bachelor of Medicine and Surgery (MB BChir) 1st year student Functions of the Digestive System The functions of the digestive system are: 1. Ingestion. Food must be placed into the mouth before it can be acted on; this is an active, voluntary process called ingestion. 2. Propulsion. If foods are to be processed by more than one digestive organ, they must be propelled from one organ to the next; swallowing is one example of food movement that depends largely on the propulsive process called peristalsis (involuntary, alternating waves of contraction and relaxation of the muscles in the organ wall). 3. Food breakdown: mechanical digestion. Mechanical digestion prepares food for further degradation by enzymes by physically fragmenting the foods into smaller pieces, and examples of mechanical digestion are the mixing of food in the mouth by the tongue, churning of food in the stomach, and segmentation in the small intestine. 4. Food breakdown: chemical digestion. The sequence of steps in which large food molecules are broken down into their building blocks by enzymes is called chemical digestion. 5. Absorption. Transport of digested end products from the lumen of the GI tract to the blood or lymph is absorption, and for absorption to happen, the digested foods must first enter the mucosal cells by active or passive transport processes. 6. Defecation. Defecation is the elimination of indigestible residues from the GI tract via the anus in the form of feces.