BIOL164Ch15NotesWin12

BIOL164Ch15NotesWin12 - The overall idea to obtain...

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1 Ch. 15 – The Digestive System • The overall idea : to obtain nutrients from food (for energy and raw materials for synthesis), and defecate the leftover waste • There are 2 types of organs involved : –1 . Parts of the digestive tract (= a long muscular tube from the mouth to the anus) • It is a.k.a. the gastrointestinal (GI) tract • It is made up of the mouth (oral cavity), pharynx, esophagus, stomach, small intestine, and large intestine • Food passes through these –2 . Accessory organs = the teeth, tongue, salivary glands, liver, gallbladder, and pancreas • Food does not pass through these The general functions of the digestive system •1 . Ingestion = eating •2 . Mechanical digestion (e.g. by the teeth and stomach) = physically breaking, crushing, and tearing food into smaller pieces – This increases the surface area for attack by enzymes – Smaller pieces are easier to move •3 . Chemical digestion = the breaking of chemical bonds (usually by enzymes) –P r o t e i n s amino acids – Triglycerides glycerol + fatty acids – Polysaccharides
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2 An overview of the digestive organs Figure 15.1 The general histology of the wall of the digestive tract The epithelium varies by location (e.g. the mouth has stratified squamous to resist abrasion; the small intestine has simple columnar for secretion and absorption) It contains loose (areolar) CT, N.A.V.a.L., glands, and autonomic nerve plexuses (= the “brain” of the gut) (hollow space) For mixing and propelling food forward along the tract Figure 15.2
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3 Lumen (interior hollow space) Serosa not shown An example of the histology of the digestive tract wall: the duodenum of the small intestine The mouth (oral cavity) • Functions that occur here : – Begin mechanical digestion (by the teeth and tongue) – Begin chemical digestion (by salivary enzymes) – Monitor food quality/taste (by the tongue) – Moisten and manipulate food to prepare for swallowing (by saliva and the tongue, respectively) Figure 15.5a
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4 Teeth Periodontal ligament Function : mechanical digestion (via chewing) Periodontal ligament – = dense CT that, along with cementum , anchors the tooth in its socket Tooth composition : –1 . Dentin = the bulk of the tooth • = calcified CT • Is similar to, but harder than bone (it has [Ca 2+ ]) – 2. The pulp cavity within the crown • Contains pulp (= N.A.V.a.L.) • Exits via the root canal –3 . Enamel
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This note was uploaded on 03/12/2012 for the course BIOL 164 taught by Professor Tonychennault during the Winter '12 term at Clark College.

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BIOL164Ch15NotesWin12 - The overall idea to obtain...

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