chapt08LectureOutlines

chapt08LectureOutlines - 1 Chapter 8 Digestive System and...

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Unformatted text preview: 1 Chapter 8 Digestive System and Nutrition 2 Outline Overview of Digestion The First Part of the Digestive Tract The Stomach and Small Intestine Three Accessory Organs and Regulation of Secretions The Large Intestine and Defecation Nutrition and Weight Control ( Should review Ch.2 , Molecules of Life , pp. 22-30 ) 3 Overview of Digestion Also called the alimentary tract , g astroi ntestinal tract ( G.I. tract ), gut . From the mouth to the anus. There are two types of digestive processes: 1. Mechanical. . . . 2. Chemical. . . . Digestion of food is an extra cellular process due to enzymes secreted into the gut by glands that reside in the lining or lie nearby. 4 Overview of Digestion Functions of this system include: Ingest food. Digest it into small molecules that can cross the cell membrane. Movement of contents along tract. Absorb nutrient molecules. Eliminate nondigestible wastes. 5 6 7 The Wall of the Digestive Tract Layers from inside, out: ( MSMS ) Mucosa- Mucus membrane layer. Submucosa- Submucosal layer. Muscularis Longitudinal and circular smooth muscle layer. Serosa- Serous membrane layer. Disorders : Diverticulosis , diverticulitis , inflammatory bowel disease (IBD), irritable bowel syndrome (IBS), appendicitis , peritonitis . 8 9 The Digestive Tract Mouth : Food Receiver Functions : ingest, break down (mechanical), begin digestion (chemical), taste, form into bolus for swallowing. Roof of the mouth composed of two parts. Anterior (front) hard palate . Posterior (back) soft palate . Tonsils help protect against infection. Three pairs of salivary glands (exo crine glands) send juices through ducts to the mouth. Saliva contains digestive enzymes (bicarbonate and salivary amylase). 10 The Digestive Tract Mouth : Food Receiver Teeth used to chew food into pieces small enough to swallow. Each tooth has two main divisions. Crown. Root. Tongue mixes chewed food with saliva and forms a bolus in preparation for swallowing. 11 12 The Pharynx : A Crossroad The pharynx (throat) receives air from the nasal cavities and food from the mouth. Swallowing is a reflex action that occurs in the pharynx. Soft palate moves to close off nasopharynx , and the trachea moves under the epiglottis to cover the glottis . 13 Swallowing 14 The Esophagus : A Food Conductor Function ? The esophagus is a muscular tube that passes from the pharynx through the thoracic cavity and diaphragm into the abdominal cavity. Rhythmic peristalsis pushes food along the digestive tract....
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This note was uploaded on 01/17/2012 for the course BIOL 103 taught by Professor Robertwest during the Spring '12 term at Lee.

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chapt08LectureOutlines - 1 Chapter 8 Digestive System and...

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