DigestiveSystem

DigestiveSystem - Digestive System Overview The digestive...

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Unformatted text preview: Digestive System Overview The digestive system consists of a single tube running through the body (the alimentary canal) and associated (accessory) organs. The digestive system carries out four functions: Ingestion Digestion Absorption Elimination Alimentary Canal The alimentary canal is also known as the gastrointestinal tract or gut. It begins at the mouth and ends at the anus. It is a one way passageway for food and waste material. Most of the canal lies within the ventral body cavity and not within the body wall. Alimentary Canal Wall The wall of the alimentary canal consists of four major layers along most of its length: Mucosa epithelium, lamina propria, muscularis mucosae Submucosa glands, blood vessels, and nerves Muscularis externa circular and longitudinal smooth muscle layers Serosa visceral serous membrane continuous with the parietal serosa Alimentary Canal Wall Alimentary Canal The organs of the alimentary canal are the: Mouth and oral cavity Pharynx Esophagus Stomach Small intestine Large intestine Rectum and anus Accessory Organs The accessory organs include: Tongue Teeth Salivary glands Liver Gall bladder Pancreas Vermiform appendix Digestive Organs Oral Cavity The anterior opening of the oral (buccal) cavity is the mouth. Posterior opening to the oropharynx is the fauces. Bounded by the lips, cheeks, palate, and tongue. Lined with non-keratinized stratified squamous epithelium to resist abrasion. Site of initial ingestion and physical and chemical digestion. Oral Cavity Lips and Cheeks Lips and cheeks have a core of skeletal muscles Lips: orbicularis oris Cheeks: buccinators Vestibule bounded by the lips and cheeks externally, and teeth and gums internally Oral cavity proper area that lies within the teeth and gums Labial frenulum median fold that joins the internal aspect of each lip to the gum Oral Cavity Palate Hard palate underlain by palatine bones and palatine processes of the maxillae Assists the tongue in chewing Slightly corrugated on either side of the raphe (midline ridge) Soft palate mobile fold formed mostly of skeletal muscle Closes off the nasopharynx during swallowing Uvula projects downward from its free edge Palatoglossal and palatopharyngeal arches form the borders of the fauces Tongue Occupies the floor of the mouth and fills the oral cavity when mouth is closed Functions include: Gripping and repositioning food during chewing Mixing food with saliva and forming the bolus...
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DigestiveSystem - Digestive System Overview The digestive...

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