chapter 23 The digestive system.txt

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  1. The digestive system
    • Consists of the alimentary canal that includes
    • Mouth, pharynx, esophagus, stomach, small intestine, large intestine, rectum and anus
    • Accessory organs
    • Salivary glands, pancreas, liver, and gallbladder
  2. The digestive system has two main functions
    • Digestion: mechanical and chemical break down of food
    • Absorption: transporting the food in to the blood
  3. The digestive system is location
    • the abdominal cavity
    • when uncoiled becomes 8m long

    • What is food
    • Nutrients: substances needed for body growth and maintenance
    • Carbohydrates, lipids, proteins, vitamins, minerals, and water
  4. Where do nutrients come from?
    • Carbohydrates,
    • Mostly from plants
    • Some from milk
    • Bread
    • Lipids
    • Oil from animal products
    • Oil from seeds and vegitable oil
    • Egg yolks, meats, milk
    • Protein
    • Mostly from animal
    • Legumes and beans
    • Vitamins
    • Found in all major food
    • Minerals
    • Found in vegetables, legumes, milk, and some meats
  5. Histological composition of the alimentary canal
    • Consists of four distinct layers
    • Mucosa
    • Inner most layers that consists of epithelium and connective tissue
    • Secretes enzymes
    • Submucosa
    • Loose connective tissue and blood vessels
    • Muscuilaris
    • Smooth muscle layer
    • Serosa
    • Visceral peritoneum
    • Made of simple squamous and connective tissue
  6. Peristalsis
    • Movement of food by wave like motion down the alimentary canal
    • Achieved by muscularis layer
  7. Salivary glands
    • Three major glands
    • Parotid, submandibular, and sublingual
    • Secrets mucus
    • Secret enzymes AMYLASE which digests carbohydrates
  8. Stomach
    • Medially connected to esophagus and laterally connected to the duodenum
    • Has two sphincters which are rings of smooth muscle tissue acting as a valve
    • Esophageal sphincter: prevents back flow of food
    • Pyloric sphincter: controls the rate of gastric emptying
  9. Function of the stomach
    • Receives food from esophagus
    • Mixes food
    • Release enzyme that start protein digestion
    • Caries limited absorption
    • Moves food to the small intestine
  10. Lining of the stomach
    • Gastric pits are folding within the mucosal layer that contains epithelial cells
    • Mucous cells secrete mucus
    • Parietal cells secret hydrochloric acid
    • Chief cells secrete pepsin that digests proteins
  11. Accessory organs: pancreas
    • Associated with the duodenum
    • Produces pancreatic juices that consists of many enzymes
    • Pancreatic amylase: digest carb
    • Lipase: digest fat
    • Nuclease: digest nucleic acid
    • Trypsin and chymotrypsin: digest proein
  12. Accessory organs: gallbladder
    • Located on the inferior surface of the liver
    • Stores and concentrates bile
    • Release bile in to the duodenum
  13. Accessory organs: liver
    • Has many important metabolic functions
    • Stores glucose
    • Responds to insulin and glucagon
    • Synthesizes cholesterol
    • Synthesizes plasma proteins
    • Synthesizes bile
  14. Bile
    • contains water, bile salts, bile pigments, cholesterol, and electrolytes
    • function aids digestive enzyme by breaking large fat globules in to small droplets (emulsification)
  15. Small intestine
    • Consists of three portions
    • Duodenum, jejunum, ileum
    • Contains a double layer membrane called mesentery that holds the small intestine together and support blood vessels
    • Intestinal villi are tiny projections of mucous membrane that increase surface area
    • Each villus is lined with simple columnar epithelium
  16. Function of the small intestine
    • The site of pancreatic enzymes and bile release
    • Synthesizes enzymes needed for carbohydrate digestions
    • Site of fat digestion
    • Site of absorption
  17. Large intestine
    • Made of many parts
    • Cecum: where the ileocecal valve is fund
    • Vermiform appendix: lymphatic tissue
    • Colon: ascending, transverse, descending, and sigmoid
    • Rectum terminates into the anal canal
  18. Function of the large intestine
    • Has little digestive function
    • Secretes a lot of mucus to protect the lining from abrasion and to lower the acidity
    • Absorbs water and electrolytes
    • Absorbs vitamin K, B12, thiamin that are produced by bacteria called intestinal flora found in the large intestine
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chapter 23 The digestive system.txt
2011-05-27 22:08:46
chapter digestive system

chapter 23 The digestive system
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