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Biology 250: Human Anatomy

Biology 250: Human Anatomy. Spring 2005 Digestive System. Overview Of Digestive System. Alimentary System (Canal) Also Gastrointestinal (GI) Tract Continuous muscular digestive tube Digestion and absorption Mouth, pharynx, esophagus, stomach, intestines Accessory Digestive System

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Biology 250: Human Anatomy

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  1. Biology 250: Human Anatomy Spring 2005 Digestive System

  2. Overview Of Digestive System Alimentary System (Canal) • Also Gastrointestinal (GI) Tract • Continuous muscular digestive tube • Digestion and absorption • Mouth, pharynx, esophagus, stomach, intestines Accessory Digestive System • Contribute to the digestion of food • Teeth, tongue, gallbladder, liver, pancreas

  3. Digestive Processes • Ingestion • Propulsion: peristalsis • Mechanical Digestion: segmentation • Chemical Digestion • Absorption • Defecation

  4. Layers of the Alimentary Canal • Lumen: central canal where food is transported • Mucosa (Mucous Membrane): • Innermost layer; moist epithelial membrane • Secretion, absorption, protection • Submucosa: just external to mucosa • Contains blood vessels, nerve fibers • Gives walls its elastic characteristic

  5. Layers of the Alimentary Canal (Cont.) • Muscularis Externa: external to submucosa • Contains smooth muscle • Inner circular layer, Outer Longitudinal Layer • Responsible for peristalsis & segmentation • Serosa: protective outermost layer • Composed of connective tissue & epithelium

  6. The Mouth • Also called oral cavity, buccal cavity • Oral Orifice: anterior opening • Stratified Squamous Epithelium • Helps to withstand friction forces • Only organ involved with Ingestion

  7. The Lips and Cheeks • Lips (Labia) • Orbicularis Oris Muscle • Red Margin, Labial Frenulum • Cheeks • Buccinators Muscles • The two combined help keep foodbetween teeth, help with speech

  8. The Palate • Forms the roof of the mouth • Hard Palate • Food forced against it by the tongue • Soft Palate • Uvula: prevents food from traveling to the nasal cavity

  9. The Tongue • Occupies the floor of the mouth • Helps to reposition food between teeth • Occupies the taste buds • Intrinsic Muscles • Changes shape of tongue, not position • Extrinsic Muscles • Changes position of tongue, not shape

  10. The Salivary Glands • Produces Saliva Functions of Saliva • Cleanses the mouth • Dissolves food chemicals for taste • Moistens food, aids in bolus formation • Begins chemical digestion of food

  11. The Teeth • Adults contain 32 teeth • 8 incisors, 4 canines, 8 premolars, 12 molars • Crown: portion exposed above gums • Covered by enamel (hardest substance in body) • Root: portion embedded in jaws • Teeth initiate the breakdown of food • Chewing

  12. The Pharynx • Oropharynx, Laryngopharynx • Common passageway for air & food • Contain two layers of skeletal muscle • Inner: Longitudinal Muscle • Outer: Pharyngeal Constrictor Muscles • Muscles propel food into the Esophagus

  13. The Esophagus • Muscular tube; collapsed when no food • Lies posterior to the trachea • Epiglottisdirects food into esophagus • Joins the stomach at the Cardiac Orifice • Gastroesophageal Sphincter • GERD

  14. Mouth, Pharynx, Esophagus • Mastication (Chewing) • Lips, cheeks, tongue keep food between teeth • Deglutition (Swallowing) • Tongue blocks off the mouth • Uvula rises to block of nasopharynx • Larynx rises so allow epiglottis to block off the trachea and the lower airways

  15. The Stomach • Temporary storage tank of food • Coverts food into creamy paste (Chyme) Anatomical Regions of Stomach • Cardiac Region • Gastroesopageal Sphincter • Fundus • Body • Pyloric Region • Pyloric Sphincter • Greater / Lesser Curvatures • Gastric Ulcers

  16. The Small Intestine • Body’s Major Digestive Organ • Digestion completed, absorption occurs Subdivisions of Small Intestine • Duodenum • Jejunum • Ileum

  17. The Liver • Role in digestion is to produce Bile • Helps to break down fat 4 Lobes of the Liver • Right Lobe • Left Lobe • Caudate Lobe • Quadrate Lobe • Hepatitis: inflammation of liver; viral • Six types: A-F

  18. The Gallbladder • Rounded structure, connected to liver • Acts as storage site for bile • Reason for its green color • Gallstones: crystallization of bile • Causes tremendous shooting pain in abdomen • Rx: drugs, lasers, surgery

  19. The Pancreas • Found in the greater curvature of stomach • Aids in the digestion of all foods • Uses pancreatic juices for food digestion

  20. The Large Intestine • Larger diameter than small intestine • Almost half as long as small intestine • Absorbs water, eliminates waste (feces) Large Intestine Subdivisions • Cecum • Appendix • Colon: ascending, transverse, descending, sigmoid • Rectum • Anal Canal

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