Biol129_C19 - The Digestive System General A tube that...

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1 The Digestive System General • A tube that opens to the surface at both ends • Has two major subdivisions – Digestive Tract – Accessory organs • Lots of variability across mammals – Other organ systems are more constant – Diet is the largest variable
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2 Function • The digestive tract provides for: – Mechanical breakdown of food – Chemical breakdown of food – Absorption of fluids, chemicals and foods • Three biochemical classes • Vitamins, minerals, others (antibiotics) – Taste (smell) Function - 2 • Accessory organs – Assist digestion • By providing enzymes • By providing detergents – Destroying harmful compounds
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3 The Mouth • Responsible for: – Ingestion – Mechanical and limited chemical breakdown • Known as the oral or buccal cavity • Major components: – Teeth – Tongue (muscular and sensory) – Salivary glands Mouth Anatomy
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4 Teeth • Functions in mechanical digestion • There are 32 in the adult mouth • Paired across mandible & maxilla and symmetric about midline • On one side: • 2 incisors, 1 canine, 2 premolars, 3 molars • Most mammals also have deciduous teeth – Humans have 20 Teeth - 2 • Each type has a function: – Incisor – cutting • important (enlarged) in carnivores • Teeth are specialized tissue composed of: – Dentin – hard yellowish tissue – Enamel – hard surface covers crown – Cementum – in root
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5 • Enamel – placed on tooth before eruption, cannot be repaired • Dentin & cementin are • Teeth are vascularized & innervated through roots • Fixed by gomphoses in a socket (alveolus) by periodontal ligament • The gingiva (gum) covers bone Teeth - 3 Tongue • Muscular organ occupying inferior surface of the oral cavity – Quite agile and sensitive • can feel a hair (25 microns) – Covered by stratified squamous epithelia – Has lingual papillae • Site of taste buds • Specializations: Fungiform, Foliate & Vallate
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6 • Ant 2/3 – Body – Occupies oral cavity • Post 1/3 – Root – Occupies oropharynx • Intrinsic & extrinsic
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This note was uploaded on 03/31/2008 for the course BIOL 129 taught by Professor Sachshowardgeor during the Spring '08 term at Penn State.

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Biol129_C19 - The Digestive System General A tube that...

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