Digestive System

  1. Alimentary Canal
    mouth, pharynx, exophagus, stomach, small intestine, large intestine
  2. Accessory Digestive Organs
    teeth, tongue, gallbladder, salivary glands, liver, pancreas
  3. 6 Activities in Digestive Process
    • Ingestion
    • Propulsion
    • Mechanical Digestion
    • Chemical Digestion
    • Absorption
    • Defecation
  4. 1st Step in Digestive Process
    taking food into digestive tract
  5. 2nd Step: Digestive Process
    • -swallowing: tongue pushes bolus of food back and downward into the esophagus
    • -Peristalsis: waves of contraction and relaxation of muscles in the organ walls, moves food
  6. 3rd Step: Digestive Process
    Mehanical Digestion
    • 3 Processes
    • -Chewing-teeth
    • -Mixing-mouth, stomach, small intestines
    • -Churning food(Segmentation)-stomach and small intestines
  7. 4th Step: Digestive Process
    Chemical Digestion
    catabolic breakdown of food by enzymes and acid
  8. 5th Step: Digestive Process
    movement of nutrients from the GI tract to the blood or lymph (fats through lacteals)
  9. 6th Step: Digestive Process
    elimination of indigestible solid wastes
  10. Regulation of Digestion Involves:
    • 1. Mechanical and Chemical Receptor Stimuli
    • 2. Extrinsic control by CNS centers
    • 3. Intrinsic control by local centers
  11. Receptors of GI Tract:
    Mechano-and chemoreceptors
    Respond to...
    • a. Stretch of alimentary canal
    • b. osmolarity (solute concentration)
    • c. pH increases as the canal is stretched
    • d. Presence of substrate increases digestion, and end products of digestion decreases digestion

    • -Initiate Relflexes:
    • Activate/Inhibit Digestive glands, and mixes lumne contents and move along
  12. Nervous Control of GI tract:
    • Intrinsic: (short reflexes)
    • -gut brain, automatic reflexes like peristalsis and segmentation

    • Extrinsic: (long reflexes)
    • -arising within/outside GI tract
    • -sends signals to small and large intestines
  13. Peritoneum
    serous membrane of the abdominal cavity
  14. Visceral Peritoneum
    covers external surface of most digestive organs
  15. Parietal Peritoneum
    lines body wall
  16. Peritoneal Fluid
    • Lubricates organs
    • allows them to slide across from one another
  17. Mesentery
    • double layer of peritoneum that provides:
    • -vascular and nerve supplies to visceral organs
    • -hold digestive organs in place and store fat
  18. Retroperitoneal organs
    • organs outside peritoneum
    • ex) kidneys
  19. Peritoneal Organs
    • organs surrounded by peritoneum
    • ex) liver
  20. Splanchnic Circulation
    arteries that branch off the abdominal aorta to serve digestive organs and the hepatic portal circulation

    Celiac Trunk: hepatic, splenic, left gastric, spleen, liver, stomach

    Superior and Inferior Mesenteric: small/large intestines
  21. Hepatic Portal Circulation
    1. collects nutrient rich venous blood from digestive viscera

    2. delivers blood to liver for metabolic processing and storage
  22. Four Tunics: Alimentary Canal
    • 1. Mucosa-Epithelium
    • 2. Sub Mucosa-Connective Tissue
    • 3. Muscularis Externa-Muscle
    • 4. Serosa-Outer Wall
  23. Mucosa: Alimentary Canal
    • 1st Tunic:
    • -lines lumen of canal
    • -secretes mucus
    • -absorbs end products of digestion
    • -protects against infectious diseases

    Contains 3 layers: epithelium, lamina propia, muscularis mucosae
  24. Epithelial Lining: Mucosa
    (Alimentary Canal)
    • -simple columnar epithelium, mucus secreting goblet cells
    • -mucus protects digestive organs from digesting themselves
    • -ease food along tract
    • -stomach and small intestine
    • -enzyme and hormone secreting cells
  25. Lamina Propia: Mucosa
    (Alimentary Canal)
    • -loose areolar and reticular connective tissue
    • -nourishes epithelium and absorbs nutrients
    • -contains lymph nodes, defense against bacteria
  26. Muscularis Mucosae: Mucosa
    (Alimentary Canal)
    smooth muscle cells that produce local movements of mucosa
  27. Submucosa: Alimentary Canal
    • 2nd Tunic:
    • -dense connective tissue containing:
    • -elastic fibers
    • -blood
    • -lymphatic vessels
    • -lymph nodes
    • -nerves
  28. Muscularis Externa: Alimentary Canal
    responsible for segmentation and peristalsis
  29. Serosa
    protective visceral periotneum

    -replacd by fibrous adventitia in esophagus
  30. Submucosal Nerve Plexus
    • occupies submucosa
    • -sensory and motor neurons
    • -regulates activity of glands and smooth muscle in mucosa
  31. Myenteric Nerve Plexus
    • between muscle layers of muscularis externa
    • -provide major nerve supply to GI tract wall and mobility
    • -lined to long autonomic reflex arc
  32. Oral Cavity:
    In order to withstand abrasions...
    • -mouth lined with stratified squamous epithelium
    • -gums, hard palate, dorsum of tongue are slightly keratinized
  33. Lip Muscles
    Orbicularis Oris
  34. Cheek Muscles
  35. Vestibule
    bounded by lips and cheeks externally, teeth and gum internally (tobacco place)
  36. Oral Cavity Proper
    area that lies within teeth and gums
  37. Labial Frenulum
    median fold that joins internal aspect of each lip to gum
  38. Hard Palate
    • underlain by palatine bones and palatine processes of the maxillae
    • -assists tongue in chewing by being platform for food
    • -slightly corrugated on either side of raphe (midline ridge)
  39. Soft Palate
    • mobile fold formed mostly of skeletal muscle
    • -closes nasopharynx during swallowing
    • -uvula projects downward from edge, assists food with downward projection, directs food
  40. Tongue:
    • occupies floor of mouth
    • -gripping/repositioning food during chewing
    • -mixing food w/saliva =bolus
    • -initiation of swallowing and speech
  41. Intrinsic Muscles: Tongue
    change shape of tongue
  42. Extrinsic Muscles
    alter tongue position (left, right, up, down)
  43. Lingual Frenulum
    secures tongue to floor of mouth and presents tongue from sliding posterior
  44. Ankloglossia
    tongue tied, lingual frenulum too tight
  45. 3 types of Papillae on Tongue
    • 1. Filliform: roughness/friction
    • 2. Fungiform: taste, give reddish hue
    • 3. Circumvallate: V shaped row
  46. Sulcus Terminalis
    • groove that seperates tongue into 2 areas:
    • Oral Cavity=anterior 2/3
    • Oropharynx=posterior third
  47. Salivary Glands
    • -cleanse mouth
    • -moistens/dissolves food
    • -aid in bolus formation
    • -contains enzymes that break down starch
  48. 3 pairs of Extrinsic Glands:
    • Parotid
    • Submandibular
    • Sublingual
  49. Intrinsic Salivary Glands:
    • aka. Buccal Glands
    • scattered throughout oral mucosa
  50. Parotid Gland
    opens into vestibule next to second upper molar
  51. Submandibular
    ducts open at base of lingual frenulum
  52. Sublingual
    opens with 10-12 ducts into floor of mouth
  53. Xerostomia
    dry mouth
  54. Mumps
    • Epidemic Parotitis
    • -viral disease of human species, caused by mumps virus
    • -painful swelling of salivary glands (mostly parotid)
    • -testicular swelling, rash, infertility, subfertility
  55. What is saliva secreted from?
    serous and mucous cells of salivary glands
  56. Saliva is______% water, _________,
    and slightly _______ solution.
    • 1. 97-99.5
    • 2. hypo-osmotic
    • 3. acidic
  57. Saliva contains:
    • Electrolytes: NA+, K+, CL-, PO2-4, HCO-3
    • Digestive Enzyme: salivary amylase
    • Proteins: mucin, lysozyme, defensins, IgA
    • Metabolic wastes: urea and uric acid
  58. Intrinsic Salivary glands (Buccal glands)...
    keep mouth moist
  59. Extrinsic salivary glands....
    • secrete serous, enzyme-rich saliva in response to:
    • -ingested food stimulating chemoreceptors and pressoreceptors
    • -thought of food
  60. What does strong sympathetic salivation do to salivation?
    inhibits salivation and results in dry mouth
  61. By age ____ primary and permanent dentitions of teeth form.
  62. Primary Teeth
    20 deciduous teeth that erupt at intervals between 6 and 24 months.
  63. Permanent
    englarge and develop causing root of deciduous teeth to be resorbed and fall out between ages 6 and 12.
  64. Usually about ___ permanent teeth
  65. Name the types of teeth:
    • Incisors
    • Canines
    • Premolars
    • Molars
  66. Crown:
    exposed part of tooth above the gingiva
  67. Enamel:
    acellular, brittle material composed of calcium salts and hydroxyapatite crystals is the hardest substance in the body
  68. Root:
    portion of tooth embedded in jawbone
  69. Neck:
    constriciton where crown and root come together
  70. Cementum:
    • calcified connective tissue
    • -covers root
    • -attaches to periodontal ligament
  71. Periodontal Ligament:
    • anchors tooth in the alveolus of jaw
    • forms fibrous joint called gomphosis
  72. Gingival sulcus:
    depression where the gingiva borders the tooth
  73. Dentin:
    bonelike material deep to enamel cap that forms bulk of tooth
  74. Pulp cavity:
    cavity surrounded by dentin that contains pulp
  75. Pulp:
    connective tissue, blood vessels, and nerves
  76. Root canal:
    portion of pulp cavity that extends into root
  77. Apical foramen:
    proximal opening to the root canal
  78. Odontoblasts:
    secrete and maintain dentin throughout life
  79. Dental cavities (caries)
    • gradual demineralization of enael and dentin by bacterial action
    • -acid produced by bacteria in plaque dissolves calcium salts
    • -without salts, organic matter is digested by proteolytic enzymes
    • -daily flossing and brushing help prevent cavities by removing forming plaque
  80. Gingivitis:
    as plaque accumulated, it calcifies and forms calculus, or tartar
  81. Problem with accumulation of calculus:
    • disrupts seal between gingivae and the teeth
    • puts gum at risk for infection
  82. Periodontitis
    • serious gum disease resulting from an immune response
    • immune system attacks intruders as well as body tissues, carving pockets around teeth and dissolving bone
  83. Halitosis
    • odors produced mainly due to anaerobic breakdown of proteins.
    • Bad Breath:
    • 1. Anerobic bacteria of tongue
    • 2. Nasal sinus infection and gum infections
    • 3. Stomach reflux

    • Smell caused by:
    • 1. Food
    • 2. Obesity
    • 3. Smoking
Card Set
Digestive System
Part A Of Digestive System