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Name:Period:Date:DIGESTIVE SYSTEM Study GuideChapter 14 Marieb text* = page number in Marieb textbookOverviewList the organs of the alimentary canal in order from beginning to end. *412Oral cavity pharynx esophagus stomach small intestine large intestineWhat are the 6 major functions of the gastrointestinal tract? Briefly define each. *424-425Ingestion: taking food into oral cavityPropulsion: movement of food from one organ to nextChemical digestion: breaking down food with enzymesMechanical digestion: breaking down food physically (ex: teeth, muscle layers in stomach)Absorption: taking nutrients into bloodDefecation: removal of materials cannot digestName the 4 tissue layers of the GI tract from innermost to outermost, and describe the function of each. *415-417Mucosa: produces mucus to reduce frictionSubmucosa: contains blood & nervesMuscularis externa: layers of smooth muscle for peristalsisSerosa: protection of organs to prevent frictionWhat is peristalsis? *424, 427Alternating contraction and relaxation of smooth muscles to move food down digestive tractStructure and FunctionsWhat is the function of the epiglottis during swallowing? *427Covers the airway so food doesn’t get down respiratory tractWhich organ of the digestive system is the longest? Why is this (what processes happen here)? *418Small intestineLots of digestion and 90% of absorption happens here!What is the function of the mucus secreted by glands in the stomach and small intestine? *418To prevent friction so food can move down the digestive tractAnd*protects organs against acidic gastric juicesWhat are the three portions of the stomach? In what portion does the most digestive activity occur? *417Fundus, body, pylorus*most digestion happens in funnel shaped PYLORUSWhy does the stomach wall have 3 layers of muscle (instead of 2)? *418, 429There are 3 layers of smooth muscle for mechanical digestion in the stomachWhy is the esophagus lined with stratified squamous epithelium (instead of simple columnar like the other gastrointestinal organs)? *415Layers of cells help to protect esophagus & prevent frictionFood enters the stomach from the esophagus through which valve? *416, 417Cardioesophageal valveFood enters the small intestine from the stomach through which valve? *416, 417Pyloric valveFood enters the large intestine from the small intestine through which valve? *418, 420ileocecal valveWhat is the location and function of the greater omentum? *418“lacy apron” that hangs down from the greater curvature of the stomach over the intestinesWhat is the mesentery? *417Membrane of the small intestine that connects it together and to the posterior abdominal wallWhat are villi, where are they found, and what is their function? *419Finger-like projections that increase the surface area of the small intestine for 90% of ABSORPTIONWhat is the first section of the small intestine, where most enzymatic secretions enter called? *418duodenumWhat are the major functions of the large intestine? *419-420Water absorptionMaterials that can’t be digested are defecatedHow did the large intestine get its name and what is the major absorptive function of the large intestine? *419Larger in diameterAbsorbs waterName at least 4 accessory organs of the digestive system and briefly describe their functions. *421-422Liver: makes bile that breaks down fatsGallbladder: stores bilePancreas: makes enzymes that break down all organic molecule groupsSalivary glands: enzymes that break down fats and carbohydratesChemical DigestionWhat is the difference between mechanical and chemical digestion? Which organ begins both processes? *424Mechanical digestion is physical breakdown of foodChemical digestion is breakdown by enzymesBoth start in ORAL CAVITYWhat is the function of bile? Which organ produces it and which organ stores it? *421Bile breaks down fatsMade in liverStored in gallbladderName the specific organ locations and enzymes (amylase, lipase, pepsin) involved in the digestion of *426Carbohydratesb. Lipidsc. ProteinsSalivary amylase (oral cavity) breaks down carbohydratesSalivary lipase (oral cavity) breaks down fatsPepsin in the stomach breaks down proteinsThe stomach produces hydrochloric acid (HCl) – what is its function in digestion? *429Activates enzymesWhat is chyme? *418Semi-fluid contents of the stomach – which is gastric juices mixed with food What organic compound groups do secretions from the pancreas break down? What section of the small intestine do these pancreatic secretions enter? *421The pancreas secretes enzymes that break down all of the organic molecule groups (carbohydrates, lipids, proteins). The pancreas releases these enzymes into the duodenum of the small intestine.Disorders and DiseasesWhat is heartburn? What causes this condition? *429Heartburn is a condition when the cardioesophageal valve doesn’t close tightly and gastric juices from the stomach backflow into the esophagus.28) Briefly describe the following conditions:a. jaundice *421Bile pigments in the body cause the tissues to become yellow. This condition is due to blockage of ducts or liver problems.b. hepatitis *421Inflammation of the liver.c. cirrhosis *421Chronic inflammatory condition in which the liver is severely damaged. This condition is almost guaranteed when one drinks alcoholic beverages in excess for many years.d. ulcers *428Hole in the mucosa layer of the GI tract. When in the stomach it is called a peptic ulcer.e. diarrhea and constipation *433Diarrhea is a condition of watery stools, resulting when food rushes through the large intestine before water is absorbed.Constipation may result from lack of fiber in diet. Too much water is absorbed because food residue is in the large intestine for a longer period of time.29) *** PIZZA PATHWAY - Trace the pathway of a piece of pizza through the digestive tract. Be sure to include all ORGANS and all VALVES. (For now – you can LIST)Give the major FUNCTION(S) of each organ in digesting the pizza.DIGESTIVE PATHWAY CHART Main Functions of Organ or Name of ValveOral Cavity Food taken into oral cavity by ingestionMechanical digestion by teethChemical digestion by enzymesPharynxFood bolus enters pharynxPassageway for both food and airEsophagusThis is a “food chute”Food moves by propulsionValve between Esophagus and StomachCardioesophageal valveStomachChemical digestion by pepsin (enzyme that breaks down proteins)Mechanical digestion by 3 layers of muscularis externaValve between Stomach and Small IntestinePyloric valveSmall IntestineMajority of absorption into blood through villiValve between Small and Large IntestinesIleocecal valveLarge IntestineRemaining water absorbedFeces eliminated through process of defecationDiagrams to STUDYOverview of Digestive System *413Oral Cavity *414Layers of the Gastrointestinal Tract *415Stomach *416*Short Answer “Essay” Review Questions – Page 452Answer the following questions, in complete sentences, in the space provided below.FOUR Questions: Short Answer Essay Questions #’s 12, #14, #20, and At the Clinic #3. Short answer # 12) It is necessary for the stomach contents to be so acidic because hydrochloric acid (HCl) activates enzymes. For example, it activates pepsin to break down proteins.The stomach is able to protect itself because the mucosa layer of the digestive tract secretes mucus.Short answer # 14) Fatty stools result from absence of bile and/or pancreatic juice because bile is produced in the liver and stored in the gallbladder and its function is to chemically breakdown fats.Pancreatic enzymes include lipase which breaks down fats. Pancreatic enzymes can break down all organic molecule groups.Short answer # 20) Most nutrient absorption occurs in the small intestine which is the longest organ of the digestive tract. About 90% of absorption happens here through the villi.At the Clinic #3)Gastric ulcers are holes in the mucosa layer due to acidic gastric juices that contains hydrochloric acid (HCl). The prescribed medication promotes healing and reduces inflammation. Drugs that inhibit secretion of HCl (like Zantac) may be prescribed.Peptic ulcers cab produce serious complications like bleeding in digestive tract, vomiting of blood and blood in the feces. In severe cases peritonitis or damage to nearby pancreas can result.Potential causes of ulcers (which can also make existing ulcers worse) are smoking, alcohol, and aspirin. Aspirin would make the ulcer worse. ................
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