Chapter 22 - Chapter 22 Microbial Diseases of the...

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Chapter 22 Microbial Diseases of the Gastrointestinal Tract Structures of the digestive system Divided into two parts: The gastrointestinal tract (GI tract) The pathway from the mouth to the anus Accessory digestive organs Organs involved in grinding food or providing digestive secretions Salivary glands Liver Gallbladder Pancreas The function of GI tract digests food absorbs nutrients and water into the blood and eliminates waste Components of the gastrointestinal tract Mouth-site where food is moistened and chewed Esophagus-tube leading to the stomach Stomach-secretes HCl, enzyme: pepsin Small intestine- digestion and absorption of nutrients Large intestine (colon)-completes absorption of nutrients: water, steroids and minerals Rectum and anus eliminate waste Normal Microbiota of the Digestive System Tongue, teeth, small intestine, colon, rectum Heavily colonized with various bacteria Oral cavity contains up to 700 different bacterial species Esophagus, stomach, duodenum “almost sterile” – how can that be? HCl in stomach; peristalsis and the rapid transport of food helps prevent colonization by microbes MICROBIAL DISEASES OF THE DIGESTIVE SYSTEM Dental Caries (Tooth Decay) Accumulation of microbes on the surface of the teeth is called dental plaque -biofilm. The plaque is made up of streptococci ( Streptococcus mutans ) and filamentous bacteria Actinomyces Bacteria hydrolyze the sucrose into glucose and then use glucose to synthesize dextran (gummy polysaccharide) Inside the plaque, bacteria ferment the fructose into lactic acid. Lactic acid damages the enamel of the tooth Bacteria invade the dentin (calcified tissue of a tooth) Bacterial population inside the dentin is composed of Gr+ bacilli and filamentous bacteria (about 300 bacterial species are identified)
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If not treated, the tooth decay advances to pulp and roots (contain blood vessels and nerves) The infection can spread to the neighboring soft tissue Prevention of dental caries - reducing the amount of sucrose in the diet and, proper brushing and flossing Periodontal Disease Initial stage – gingivitis
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This note was uploaded on 12/13/2011 for the course BIO 0019 taught by Professor Spencer during the Fall '11 term at Broward College.

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Chapter 22 - Chapter 22 Microbial Diseases of the...

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