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# Digestive System ## Function The digestive system's function is to digest food and absorb nutrients. ## Digestion Process * **Mechanical Digestion:** Cutting, crushing, grinding food. * **Chemical Digestion:** Enzymes break down food substances (HCl, Bile). ## Anatomy and Physiology of th...

# Digestive System ## Function The digestive system's function is to digest food and absorb nutrients. ## Digestion Process * **Mechanical Digestion:** Cutting, crushing, grinding food. * **Chemical Digestion:** Enzymes break down food substances (HCl, Bile). ## Anatomy and Physiology of the Digestive System The organs and tissues of the digestive system are categorized into two main groups: ### 1. Digestive Tract * Mouth * Pharynx * Esophagus * Stomach * Small Intestine * Large Intestine * Rectum * Anus. ### 2. Digestive Glands * Liver * Pancreas (exocrine) * Salivary glands * Intestinal glands ## Detailed Description of Each Part: ### 1. Mouth * **Function:** Chewing food and forming the bolus. * **Parts:** * Lips (sensitive to taste) * Teeth (incisors for cutting, canines for tearing, premolars and molars for grinding). * Tongue (assists in swallowing and tasting). * **Note:** The wisdom teeth (third molars) are vestigial in humans (no longer needed). ### 2. Pharynx (Throat) * **Function:** The junction of the digestive and respiratory systems. The epiglottis covers the airway during swallowing. ### 3. Esophagus * **Function:** Connects the pharynx to the stomach. Food moves through the esophagus via peristalsis (muscle contractions). ### 4. Stomach * **Function:** The stomach uses mechanical and chemical digestion. Peristaltic movements churn food. Chemical digestion includes pepsin (breaks down proteins) and HCl (hydrochloric acid) to create chyme. ### 5. Small Intestine * **Structure:** Three sections (duodenum, jejunum, ileum). The surface area is increased by folds (plicae circulars), villi, and microvilli. * **Function:** The small intestine absorbs nutrients into the bloodstream. Digestive enzymes from the pancreas and bile from the liver aid in the process. Chyme is transformed into chyle. ### 6. Large Intestine * **Structure:** Four sections (cecum, ascending colon, transverse colon, descending colon, rectum, anus). * **Function:** Absorbs water and forms feces.