1. DYGESTIVE SYSTEM BY ELENA ANTON

4. Six basic functions: 1. Ingestion. Foods and liquids into the mouth (eating). 2. Secretion. Digestive organs secrete a total of about 7 liters of water, acid, buffers, and enzymes into the lumen of the tract. 3. Mixing and propulsion. Alternating contraction and relaxation of smooth muscle in the walls of the GI tract mix food and secretions and propel them toward the anus. 4. Digestion. Mechanical and chemical processes break down ingested food into small molecules. 5. Absorption. The entrance of ingested and secreted fluids, ions, and the products of digestion into the epithelial cells lining the lumen of the GI tract . The absorbed substances pass into the blood or lymph and circulate to cells throughout the body. 6. Defecation. Wastes, indigestible substances, bacteria, cells sloughed from the lining of the GI tract, and digested materials that were not absorbed leave the body through the anus in a process called defecation. Function of Digestive System

5. The mucosa is a mucous membrane composed of: 1. The epithelium in the mouth, pharynx, esophagus, and anal canal is mainly nonkeratinized stratified squamous epithelium that serves a protective function. Located among the epithelial cells are exocrine cells that secrete mucus and fluid into the lumen of the tract, enteroendocrine cells, secrete hormones. 2. The lamina propria is an areolar connective tissue layer containing many blood and lymphatic vessels that carry the nutrients absorbed by the GI tract to the other tissues of the body. The lamina propria contains mucosa-associated lymphoid tissue (MALT ). MALT is present all along the GI tract, especially in the tonsils, small intestine, appendix, and large intestine, and it contains about as many immune cells 3. Muscularis mucosae is a thin layer of smooth muscle fibers that causes the mucous membrane of the stomach and small intestine to form many small folds, increasing the surface area for digestion and absorption Mucosa of GI Tract

9. Layers of the GI Tract

16. Salivary Glands

25. Anatomy of the Stomach

30. 1. Hepatocytes are the major functional cells of the liver and perform a metabolic, secretory, and endocrine functions. Hepatocytes form complex three-dimensional arrangements called hepatic laminae. The hepatic laminae are plates of hepatocytes, grooves in the cell membranes between neighboring hepatocytes provide spaces for canaliculi into which bile is secreted. 2. Bile canaliculi small ducts between hepatocytes passes into bile ductules and then bile ducts. The bile ducts merge and eventually form the larger right and left hepatic ducts, unite and exit the liver as the common hepatic duct . The common hepatic duct joins the cystic duct from the gallbladder to form the common bile duct. 3. Hepatic sinusoids blood capillaries between rows of hepatocytes that receive oxygenated blood from branches of the hepatic artery and nutrient-rich deoxygenated blood from branches of the hepatic portal vein. Hepatic sinusoids converge and deliver blood into a central vein. From central veins the blood flows into the hepatic veins, which drain into the inferior vena cava.