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Download The Upper Alimentary System
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The Upper Alimentary System Layers of the Alimentary Canal • Mucosa – Mucous Membrane • innermost layer • adjacent to lumen • Primarily epithelial tissue • Secretes mucous and other products to aid in digestion. • Submucosa • Below mucosa • Dense connective tissue • Contains blood vessels, lymphatic, vessels, nerves Layers of the Alimentary Canal • Muscularis Externa • Two layers of smooth muscle to aid in peristalisis and mechanical digestion • Serosa • Thin, slippery membranes that minimize friction between organs and cavity wall. • Also known as peritoneum • visceral • Parietal • Connected together by the mesentery THE ALIMENTARY CANAL • Alimentary Canal • Also known as the gastrointestinal tract (gi tract) • The tube that runs through the body from the mouth to the anus. • 30 feet long and includes the pharynx, esophagus, stomach, small and large intestines. • Accessory Organs/Structures Teeth Salivary glands Liver Pancreas Gallbladder Upper Alimentary/Organs • Oral Cavity • Ingestion • Mechanical breakdown- mastication (chewing) • Chemical breakdown- salivary enzymes • Propulsion- pushing food back to throat to swallow • Teeth, gingiva, tongue, salivary glands, cheeks and lips all assist Teeth Responsible for mechanically breaking down food • Anatomy of Tooth • Crown – visible portion doing the chewing, covered in enamel • Root – below the gums and bone; anchored to the jaw via ligaments • Pulp- Cavity inside tooth with blood and nerve supply • Three tissue layers • Enamel- Outer most layer of tooth, mineral calcium phosphate similar to bone but much harder • Cementum and dentin are underlying tissues within the tooth • Periodontium- tissue surrounding teeth • Gingiva (gums)- soft • Boney socket for tooth to anchor Salivary Glands • Responsible for chemically breaking down food by secreting saliva into mouth • Saliva- moistens food, protects mouth and body from infection • Water, enzymes, mucous, antibodies • Three pairs of salivary glands • Parotid • Submandibular • Sublingual Pharynx & esophagus • The pathway (within alimentary canal) food takes on its way to the stomach from the mouth • Pharynx- the throat • Esophagus- muscular food tube to stomach peristalsis begins (wave of muscular contraction to push food through the gi tract *** note we share this space with the respiratory system… so don’t get these structures confused!! Stomach • Responsible for mechanically & chemically breaking down food by secreting gastric juices • Anatomy of Stomach Cardioesophageal sphincter Stomach • The stomach is basically a reservoir, a holding tank for food and stretches out to hold 2 liters of contents. Food takes a while to break down and must be broken down before entering the small intestine for nutrient absorption. The stomach does most of the heavy work for digestion • Rugae- folds of tissue that allow the stomach to expand when full with food • Mechanical digestion •Lined with three layers of muscles to churn food, continue chopping after the teeth are done • Chemical digestion food + gastric •Inner layer of the stomach • Simple columnar epithelium that secretes mucus. • Gastric pits that secrete juices • Hydrochloric acid (HCl) juices = CHYME!
