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Chapter 8 Digestive System Learning Outcomes 1.Describe the digestive system. 2.Explain the primary functions of the organs of the digestive system. 3.Describe the two sets of teeth found in humans. 4.Identify the three main portions of a tooth. Learning Outcomes 5.Discuss the accessory organs of the digestive system and state their functions. 6.Analyze, build, spell, and pronounce medical words. 7.Describe diagnostic and laboratory tests related to the digestive system. Key words/Combo Forms Difference b/w exocrine and endocrine Know the combining forms on page 219 Prand/i = meal Proct/o = anus and rectum Hepat/o = liver Ondot/o = tooth Knowing these will help you break down medical words listed in 219-236 Bolus Journey Path Mouth/Teeth/ Liver Salivary Glands Gallbladder Pharynx/Esophagus Pancreas Stomach Small Intestine Large Intestine Highlight procedures and drugs Group Work/Individual Work Visuals/Overviews for parts of the digestive system List functions according to selected region or area List key combining forms for specific area (e.g., liver is hepat/o, or labi/o is lip) Create One Multiple Choice Question Figure 8.1 Digestive system. TABLE 8.1 Digestive System at-a-Glance YouTube- An Overview http://www.dnatube.com/video/8362/Animatio n-of-the-digestive-system Resources https://www.nlm.nih.gov/medlineplus/digestivesy stem.html Anatomy and Physiology Overview General description of the digestive or gastrointestinal system: a continuous tube beginning with the mouth and ending at the anus. This tube is known as the alimentary canal and/or gastrointestinal tract and is about 30 feet long in adults. Anatomy and Physiology Overview Digestive system contains both primary and accessory organs for the conversion of food and fluids into a semiliquid that can be absorbed for the body to use. Three main functions: Digestion Absorption Elimination https://youtu.be/5_BiPdWRVCw TABLE 8.2 Components of Chemical Digestion Mouth Tongue = Lingu/o: Made of skeletal muscle and covered with mucous membrane Can be divided into: Root Pointed tip Central body Papilla(e) (elevations) and taste buds (sweet, salt, sour, and bitter) are located on the tongue's surface. Figure 8.2 (continued) Oral cavity: (B) anterior view as seen through the open mouth. Teeth Two Sets 20 deciduous teeth, also referred to as milk teeth or baby teeth 32 permanent teeth 8 incisors 4 canines 8 premolars 12 molars Teeth Each tooth consists of three main portions: Crown Neck Root Figure 8.4 Teeth. (A) Diagrammatic section through a typical adult tooth. Figure 8.4 (continued) Teeth. (B) The adult teeth. Epiglottis – break it down Figure 8.3 Movement of a bolus of food from the mouth to the esophagus. The bolus then travels to the stomach. Pharynx Pharynx A chamber that extends between the internal nares and the entrance to the larynx and esophagus Pharynx (Pharynge/o) The pharynx is a common passageway for both respiration and digestion. Both the larynx, or voice box, and the esophagus begin in the pharynx. The epiglottis (a flap of tissue) blocks the opening of the larynx, preventing food from entering the airway leading to the trachea (windpipe). Esophagus A muscular tube about 10 inches long that leads from the pharynx to the stomach. The lower esophageal or cardiac sphincter is at the junction with the stomach. This esophageal sphincter: relaxes to permit passage of food. contracts to prevent the backup of stomach contents. Esophagus = Esophag/o Food is carried along the esophagus by a series of wavelike muscular contractions called peristalsis. https://youtu.be/KJaM34vmMhs Stomach = Gastr/o A muscular, distensible saclike portion of the alimentary canal between the esophagus and duodenum. Fundus: upper region of the stomach. Body: the main portion. Antrum: the lower region. Rugae: folds in the mucous membrane lining the stomach https://youtu.be/Yoo91B3aVbw Figure 8.5 Stomach = Gastr/o Small Intestine About 21 feet long and 1 inch in diameter. Extends from pyloric sphincter at base of stomach to entrance of large intestine. Divided into three parts: Duodenum (doo″o-de´num) Jejunum (jĕ-jū'nŭm) Ileum (il'ē-ŭm) Do not confuse this word with ilium. Figure 8.6 Small intestine. Small Intestine Chyme is mixed with bile and pancreatic juice. Digestion and absorption take place chiefly in the small intestine. Tiny capillaries and lymph vessels absorb nutrients, which are transferred to body cells by the circulatory system. https://youtu.be/VSATCzXqLr0 Large Intestine About 5 feet long and 2.5 inches in diameter. Divided into: Cecum Colon (colon/o) Rectum (rect/o) Anal canal (proct/o = anus and rectum) https://youtu.be/oZgx_52vVTU Figure 8.7 Large intestine. Accessory Organs These organs are not actually part of the digestive tube but are closely related to the digestive process: Salivary glands Liver Gallbladder Pancreas https://youtu.be/0n6MJqmKFzY Accessory Organs Salivary Glands (Sial/o = saliva, salivary) Located in or near the mouth. Secrete saliva in response to sight, smell, taste, or mental image of food. Salivary Glands Parotid Submandibular Sublingual Figure 8.8 Salivary glands, salivary ducts and the tongue. Accessory Organs Liver = Hepat/o The largest glandular organ in the body. Weighs about 3 ½ lbs. Located in the upper right part of the abdomen. Plays an essential role in the normal metabolism of carbohydrates, fats, and proteins. Figure 8.9 Liver. Accessory Organs Carbohydrate Metabolism Changes glucose to glycogen and stores it until needed by body cells. When required, glycogen is converted back to glucose. Fat Metabolism The liver serves as a storage place and acts to desaturate fats before releasing them into the bloodstream. Protein Metabolism The liver acts as a storage place and assists in both protein anabolism and catabolism. Accessory Organs The liver manufactures the following important substances: Bile Fibrinogen and prothrombin Heparin Blood proteins The liver stores iron and vitamins B12, A, D, E, and K. Detoxifies many harmful substances (toxins), such as drugs and alcohol. Figure 8.15 The liver in this photograph was from a deceased patient with an advanced state of cirrhosis. Accessory Organs Gallbladder (Chol/e = gall, bile) A small, pear-shaped sac attached to the liver in which excess bile is stored and concentrated. Concentration is accomplished by reabsorption of water. What causes gallbladder stones? Figure 8.14 Gallbladder with gallstones. Note the stones in the hepatic duct, gallbladder, and common bile duct. http://www.niddk.nih.gov/health-information/healthtopics/digestive-diseases/gallstones/Pages/facts.aspx Accessory Organs Pancreas = Pancreat/o A large, elongated gland situated behind the stomach and secreting pancreatic juice into the small intestine. Contains cells that produce digestive enzymes. Other specialized cells secrete the hormones insulin and glucagon directly into the bloodstream. Check out here for an explanation of the endocrine and exocrine functions Figure 8.10 Pancreas. Group Work/Individual Work Visuals/Overviews for parts of the digestive system List functions according to selected region or area List key combining forms for specific area (e.g., liver is hepat/o, or labi/o is lip) Create One Multiple Choice Question