Digestive System Part 2

  1. Processes of Digestion:
    • 1. Food ingested: by mouth
    • 2. Mechanical digestion: chewing
    • 3. Chemical digestion: Salivary amylase begins chemical breakdown of starch
    • 4. Propulsion: initiated by swallowing
    • 5. Pharynx and Esophagus: pass food from mouth to stomach
  2. Pharynx
    • passes food and fluids to esophagus and gives air to trachea
    • -lined with stratified squamous epithelium and mucus glands
    • -two skeletal muscle layers for swallowing
    • 1. inner longitudinal
    • 2. outer pharyngeal constricters
  3. Deglutition
    Swallowing: involving 22 seperate muscle groups and involves 3 phases
  4. Buccal Phase:
    • (within deglutition)
    • bolus is forced into oropharynx
  5. Pharyngeal-esophageal phase:
    • (within deglutition)
    • -controlled by medulla and lower pons
    • routes sealed off except into digestive tract (probably so we don't choke)
  6. Peristalsis:
    • (within deglutition)
    • moves food through pharynx and esophagus
  7. Esophagus
    • muscular tube going from laryngopharynx to stomach
    • travels through mediastinum and pierces diaphragm
    • joins stomach at cardiac orifice
  8. Esophageal mucosa
    nonkeratinized stratified squamous epithelium
  9. What happens when the esophagus is empty?
    its folder longitudinally and flattened
  10. The muscle changes from what to what in the esophagus?
    skeletal (superiorly) to smooth muscle (inferiorly)
  11. When does a Hiatal Hernia occur?
    • when the cardiac (gastroesophageal) Sphyncter does not close when food is in stomach
    • -causes pregnancy, obesity, weak sphyncter
    • -superior stomach can move into thoracic cavity
  12. Gastro Esophageal Reflux Disease (GERD)
    • is a result with acid irritating the esophagus
    • -if chronic then esophageal cancer can result
  13. What does the salivary gland secrete?
    • Amylase: carbs-glucose
    • Lingual Lipase: fats-fatty acids
  14. What does the Stomach secrete?
    • Pepsin: proteins-polypeptides
    • HCl: pepsinogen-pepsin, destroys pathogens
  15. What does the Liver secrete?
    Bile Salts: fats-fatty acids
  16. What does the Pancreas secrete?
    • Amylase: carbs-glucose
    • Trypsin: polypeptides-peptides
    • Lipase: fats-fatty acids
  17. What do the small intestines secrete?
    • peptidase: peptides-amino acids
    • sucrase: sucrose-glucose
    • maltase: maltose-glucose
    • lactase: lactose-glucose
  18. What happens when bolus goes into stomach?
    chemical breakdown of proteins and food is converted into chyme
  19. Cardiac Region
    surrounds cardiac orifice and cardic sphincter
  20. Fundus
    dome shaped region beneath diaphragm
  21. Pyloric Region:
    • made of antrum and canal whih terminates at pylorus
    • -pylorus extends to duodenum
  22. What does the greater omentum help with?
    holding the small intestines in place
  23. What is the Nerve Supply like in the Stomach?
    sympathetic and parasympathetic fibers of autonomic nervous system
  24. Blood Supply in the stomach comes from where?
    • celiac trunk (gastric artery
    • corresponding veins (gastric veins)

    part of hepatic portal system
  25. What does the Muscularis layer do in the Stomach?
    • allows stomach to churn, mix, and pummel food physically
    • breaks down food into smaller fragments
  26. What is the Epithelial lining in the Stomach composed of?
    Goblet cells: produce double layer coat of alkaline insoluble mucus with bicarbonate in between
  27. Gastric Pits:
    contain gastric glands that secrete gastric juice, mucus, and gastrin
  28. Mucous Neck Cells (Gastric Pit)
    secrete acid mucus
  29. Parietal Cells (Gastric Pit)
    secrete HCl and intrinsic factor needed for Vitamin B12 (nucleic acid metabolism and RBC maturation) absorption in small intestines
  30. Chief Cells (Gastric Pit)
    produce pepsinogen

    (pepsinogen activated to pepsin by HCl in stomach and pepsin breaks down proteins to polypeptides)
  31. Enteroendocrine cells (Gastric Pit):
    • Secretes:
    • -Gastrin: stimulates gastric glands to increase there secretion, stimulates gastric emptying
    • -Histamine: activates parietal cells to release HCl
    • -Serotonin: stimulates gastric muscle contractions
    • -Cholecystokinin (CCK): allows pancreatic and bile enzymes to be released
    • -Ghrelin: release when stomach is empty stimulating hunger and appetite
Card Set
Digestive System Part 2
Part 2