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START ↓ **Mouth (Oral Cavity)** - Ingestion: Food enters the mouth. - Mechanical Digestion: Chewing (teeth break down food). - Chemical Digestion: Salivary amylase begins breaking down starches into maltose. - Bolus Formation: Food is moistened with saliva and shaped into a bolus. ↓ **Pharynx (Throat)** - Swallowing: Bolus moves from the mouth to the pharynx. ↓ **Esophagus** - Peristalsis: Wave-like muscle contractions move the bolus down the esophagus to the stomach. ↓ **Stomach** - Mechanical Digestion: Churning mixes food with gastric juices to form chyme. - Chemical Digestion: - Gastric juice (contains hydrochloric acid and pepsin) breaks down proteins into peptides. - Limited digestion of lipids by gastric lipase. ↓ **Small Intestine (Duodenum, Jejunum, Ileum)** - Duodenum: - Chyme is mixed with: - Bile (from the liver and gallbladder): Emulsifies fats. - Pancreatic enzymes (from the pancreas): - Amylase: Breaks down starch into maltose. - Lipase: Breaks down fats into glycerol and fatty acids. - Proteases (like trypsin): Break down proteins into amino acids. - Neutralization: Bicarbonate (from the pancreas) neutralizes stomach acid. - Jejunum & Ileum: - Absorption of nutrients through villi and microvilli: - Carbohydrates → Simple sugars (glucose). - Proteins → Amino acids. - Fats → Fatty acids and glycerol. ↓ **Large Intestine (Colon)** - Absorption: - Water and electrolytes are absorbed. - Bacteria ferment undigested carbohydrates, producing gases and short-chain fatty acids. - Formation of Feces: Undigested material and waste products form feces. ↓ **Rectum** - Storage of feces until elimination. ↓ **Anus** - Defecation: Feces are expelled from the body. ↓ END
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