Chapter 17 - Chapter 17 1) Digestion - the conversion of...

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Chapter 17 1) Digestion - the conversion of food to a soluble and a diffusible state (nutrients) A. Two types of Digestion 1. Mechanical Digestion - chewing, swallowing, mixing, peristalsis or the alternate contraction and relaxation of the muscular walls of the alimentary canal 2. Chemical Digestion - due to the presence of enzymes 2) The Alimentary Canal or Digestive Tube - consists of the mouth, pharynx, esophagus, stomach, small intestine and large intestine (colon) A. General Characteristics of the Alimentary Canal Innervation of the Tube - the autonomic nervous system's two branches: 1. Parasympathetic Nervous System - stimulates digestive activities 2. Sympathetic Nervous System - inhibits digestive activities 3) Organs of the Digestive System - consists of the six organs of the alimentary canal and the four accessory organs of digestion; namely, the salivary glands, pancreas, liver, and gallbladder. A. Mouth - oral (buccal) cavity 1. Vestibule - narrow space between the teeth, cheeks and lips 2. Frenulum - a membranous fold that connects the tongue to the floor of the mouth 3. Papillae - rough prjections on the surface of the toungue that provide friction, which is useful in handling food
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Chapter 17 4. Lingual Tonsils - rounded masses of lymphatic tissue that cover the root of the tongue (posterior region that is anchored to the hyoid bone) 5. Palate - forms the roof of the mouth and consists of a hard anterior part (maxillary and palatine bones) and a soft posterior part 6. Uvula - the cone-shaped projection of the soft palate that extends posteriorly and inferiorly 7. Palatine tonsils - masses of lymphatic tissue located in the posterior region of the mouth on either side of the tongue 8. Pharyngeal tonsils (Adenoids) - masses of lymphatic tissue located on the in the posterior wall of the nasopharynx 9. Teeth - there are 20 deciduous (primary) teeth and 32 permanent (secondary) teeth a. Functions of Teeth i. Incisors - cut food ii. Canines - grasp and tear food iii. Premoloars and molars - grind food b. Regions of the tooth i. Crown - exposed region of the tooth Enamel - hardest substance in the body; fairly brittle because it is heavily mineralized with calcium salts Dentin - bonelike material that underlies the enamel and forms the bulk of the tooth Pulp Cavity - contains connective tissue, blood vessels and nerve fibers; collectively called pulp which supplies nutrients to the tooth and provides for tooth sensations ii. Neck - area in the gums (gingiva) where the root and crown are connected iii. Root - portion of tooth that is embedded in the jawbone Periodontal Ligament (Membrane) - anchors tooth in bony jaw Cementum - superficial surface of the root; attaches root to periodontal ligament Root Canal - provides a route for blood vessels, nerves, and other pulp structures to enter the pulp cavity of the tooth B. Salivary Glands - 3 major pair produce and empty saliva into the mouth by ducts for the purpose of moistening and binding of food together to make
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This note was uploaded on 01/14/2011 for the course BIO 142 taught by Professor Unknown during the Spring '10 term at Northern Virginia Community College.

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Chapter 17 - Chapter 17 1) Digestion - the conversion of...

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