Digestion lecture

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  1. Functions of digestive tract
    • reception
    • mechanical reduction (chewing)
    • chemical absorption of food and drink
    • elimination of unabsorbed material
  2. alimentary tract
    • mouth to anus, and certain other structures connected by ducts. 
    • Inside of the GI tract is considered outside the body.  Things are only considered inside the body after going through the intestinal membrane. 
  3. Parts of the alimentary tract, in order (9)
    • lips
    • oral cavity
    • pharynx
    • esophagus
    • stomach
    • small intestine
    • large intestine
    • rectum
    • anus
  4. flank
    the side of the body between the ribs and ilium
  5. inguinal
    areas pertaining to the groin
  6. external abdominal quadrants
    right and left cranial, right and left caudal
  7. umbilicus
    the scar marking the site of entry of the umbilical cord in the fetus, also called the navel.  A surgical landmark
  8. Visceral peritoneum
    sits directly on peritoneal organs such as intestines. 
  9. parietal perinoneum
    lines abdominal wall
  10. retroperitoneal cavity
    in abdomen between abdominal wall and peritoneum.  Kidneys and adrenal gland are considered retroperitoneal
  11. Dorsal mesentery
    section of mesentery that is closest to the spine
  12. ventral mesentery
    sections of mesentery (not everywhere) that are further from the spine, surround liver
  13. Mesentery
    suspends parts of small and large intestine.  Contain blood vessels, lymphatics and nerves for the part of the GI tract they supply. 
  14. mesocolon
    suspends colon.  Part of the mesentery.  Add "meso" to any organ. 
  15. omentum
    • Double-layered connecting peritoneum between stomach and abdominal organs or abdominal wall. 
    • split into greater and lesser.
    • blanket
  16. greater omentum
    greater curvature of the stomach to body wall.  Wraps around self to create two folds.  Blanket covering intestines.
  17. lesser omentum
    stomach and duodenum to liver.
  18. Mouth
    • includes teeth, tongue and salivary glands
    • Functions: prehension (picking up), mastication (chewing), insalivation (mixing with saliva)
    • Also for agression and defense, airway and sound amplifier
  19. Outer vestibule of mouth
    lips, cheeks, oral cavity to palatoglossal arch (at ramus of mandible)
  20. lips
    • mucocutaneous border where skin meets mucuous membrane. 
    • flexible and pliable structure bounding the oral fissure. 
    • Prehension
    • long, tactile hair and regular hair
    • muscle, glands, blood vessels and nerves (5th and 7th cranial)
  21. mouth muscles
    leavtor nasolabialis, buccinator, orbicularis oris
  22. cheeks
    caudolateral wall of the oral cavity
  23. gum (gingivae)
    oral mucosa over the jaws enclosing the necks of the teeth
  24. hard palate
    • rostral bony part.  Includes palatine, maxillary and incisive bones. 
    • Palatine ridges
  25. soft palate
    caudal musculomembranous part.  Hangs off back. 
  26. Dental pad
    • replaces upper incisors and canines in ruminants. 
    • Provides heavily cornified epithelium against which the lower incisors can grind
  27. vomeronasal organ
    olfactory sense organ used to detect pheromones (carry info between animals of the same species).  In front part of top jaw, between mouth and nasal passages. 
  28. dog teeth
    • 3142/3143  =  42
    • Incisor, canine, premolar, molar. Each half. Multiply by 2 for total number.
  29. cat teeth
    • 3131/3121   =   30
    • Incisor, canine, premolar, molar. Each half. Multiply by 2 for total number.
  30. horse teeth numbers
    • 313-43/3133   =   40-42
    • Incisor, canine, premolar, molar. Each half. Multiply by 2 for total number.
  31. cow/sheep/goat teeth
    • 0033/3133  =  31
    • Incisor, canine, premolar, molar.  Each half.  Multiply by 2 for total number. 
  32. triadan system
    • system of nomenclature for teeth
    • Upper right are 100s
    • Upper left are 200s
    • lower left are 300s
    • lower right are 400s
  33. foal deciduous teeth
  34. Female horses are often missing
    canine teeth
  35. equine cheek teeth
    • slowly erupt as they are worn away--not hypsodont.  Length of reserve crown is shorter every year, so you can tell a horse's age. 
    • Form sharp ridges or "points" (lingual and buccal) and need to be "floated".
  36. part of a tooth (Dens)
    • crown (above gum)
    • root (below gum)
    • neck (between crown and root)
    • Enamel (hardest substance in body. Covers crown)
    • Dentin (bulk of tooth, surrounds pulp cavity like bone)
    • pulp (sensory, vascular part of tooth inside)
    • cementum (bone-like material covering root in a canine, whole tooth in an equine)
  37. periodontal ligament
    dense fibrous connective tissue connecting alveoli with cementum
  38. alveoli
    bone-like material that extends to the neck of the tooth.  Gums cover it. 
  39. Carnassial teeth
    large sheering teeth of cat and dog.  Premolar 4 on top and Molar 1 on bottom.
  40. wolf tooth
    a horse's rudimentary upper 1st premolar. Often absent.  Equines are always missing lower 1st premolar on lower jaw. 
  41. Canine teeth are absent/different/present in:
    • absent: mare, cow and gelding
    • present: stallion (and cat, dog, etc)
    • exaggerated: pig.  Open-rooted. 
  42. lyssa
    cartilege embedded in the tongue of a dog. 
  43. Papilli
    taste buds, mechanical and sensory functions. 
  44. muscles of the tongue
    • Intrinsic: transverse, vertical, superior longitudinal and inferior longitudinal. 
    • Extrinsic: Geniglossus, Geniohyoideus, Hypoglossus, Styloglossus
    • Canine tongue vascular to shed heat
  45. Innervation of the tongue
    • Sensation (pain, temperature and tactile) CrV Trigeminal
    • Taste (rostral two thirds) Cr XII Hypoglossal
    • Taste (caudal third) CrIX glossopharyngeal , X Vagus
    • Motor innervation Cr XII Hypoglossal
  46. Salivary glands (what and 3/4)
    • glands that empty into digestive system via ducts
    • Include: parotid, mandibular (or submandibular), sublingual, and accessory (including zygomatic)
  47. saliva
    • primarily water, some protein, glycoprotein, a significant amount of electrolytes, antibodies (IgA), mucus and enzymes. 
    • amylase: present in omnivores (pig) and to a limited degree in horse.  Absent in ruminants and carnivores (cat and dog)
  48. Parotid gland
    Salivary, encapsulated, ventral to ear, enters near premolar, long duct.
  49. Mandibular or submandibular gland
    salivary, encapsulate.  Bottom of mouth.  Sublingual.  Round. 
  50. Sublingual gland
    • Salivary gland under tongue. 
    • Has two parts: polystomatic and monostomatic
    • Dog: Poly near mouth opening, mono near jaw. 
    • Horse: only has polystomatic
    • Ruminant: have both, but positions are reversed
  51. Zygomatic gland
    one of the small, minor cheek salivary glands.
  52. nasopharynx
    top part of pharynx, respiratory section
  53. oropharynx
    lower part of distal pharynx, for food
  54. laryngopharynx
    proximal part of pharynx, common region for food and respiratory.  Where Oro- and nasopharynx meet
  55. pharynx
    • common passageway for the digestive and respiratory systems. 
    • Nasopharynx: on top, for respiratory
    • oropharynx: on bottom, for food
    • laryngopharynx: behind oropharynx, common region where both neet. 
  56. Esophagus
    • Muscular tube that transports food from oral cavity and pharynx down neck and through thorax to the stomach
    • Dorsal to and left of the trachea, caudal to diaphragm. 
    • Layers: Serosa, longitudinal muscle, circular muscle, submucosa, mucosa. 
    • In cat: distal end smooth muscle
    • In ruminants and dogs: skeletal muscle fibers run throughout
  57. layers of the esophagus
    • Lumen
    • 1. Mucosa
    • 2. submucosa
    • 3. circular muscle
    • longitudinal muscle
    • 4. serosa
  58. Cardiac sphincter
    a circular muscle that surrounds the cardia (where esophagus enters the stomach).  Has sympathetic and parasympathetic innervations
  59. deglutition
  60. Simple stomach
    • single compartment in carnivores, horse and pig. 
    • Dilating GI caudal to esophagus receives and briefly stores ingesta until muscles mix with enzymes and move into duodenum.
    • Blood supply comes from the celiac artery and goes to the portal vein
  61. Parts of the stomach
    Cardia, fundus, body, omentum (sort've), greater and lesser curvatures, pyloric antrum, ;yloric canal, pyloric sphincter
  62. Fundus
    blind expanded portion adjacent to cardia.  Often filled with gas and visible on a radiograph
  63. layers of stomach
    Lumen, mucosa, submucosa, muscle layers, serosa
  64. Glandular or non-glandular stomachs of species
    • dog and cat: glandular. 
    • Pig, horse and ruminant: composite. 
    • Luminal surface of stomach is lined by a glandular epithelium, a nonglandular epithelium or both. 
    • The fore-stomachs of a ruminant are non-glandular. 
  65. Rugae
    ridges of the lining of the stomach when it is contracted.  These stretch out when the stomach is distended. 
  66. Margo plicatus
    grossly visible line in body of stomach that separates the glandular/nonglandular tissue in a horse.  Horses have simple composite stomachs.
  67. Rumenant stomach
    • 3 forstomach chambers (reticulum, rumen and omasum) are nonglandular lined with stratified squamous epithelium. 
    • The abomasum is the glandular stomach (enzymes), on the right side next to the abdominal wall. 
    • Rumen is the fermentation vat to break down cellulose.  On the left side, it displaces organs to the right. 
    • Omasum is spherical and caudal to reticulum
  68. Small intestine
    • consists of duodenum, jejunem and ileum.  Principle digestion and absorption
    • Carnivores have a short gut, sheep have a LOOOONG gut
  69. Duodenum
    • first part of the small intestine.  Relatively short.  Receives ingesta from stomach.  Runs next to pancreas.  Mesoduodenum (attached mesentery), duodenal-jejunal flexor (bridge to jejunum). 
    • Exocrine glands: digestion enzymes
    • Endocrine glands: hormones.
  70. jejunum
    2nd part of small intestine.  Contains villi (finger-like to increase surface area) and crypts (bottom of villi, with glands).  Loops, long mesentery, lots of motion. 
  71. Ileum
    last portion of small intestine.  Indistinguishable.  Empties into large intestine through ileocolic opening.  Contains villi (finger-like projections to increase surface area), crypts (bottom of villi, with glands) and peyer's patches (lymph nodules)
  72. villi
    finger-like projections that line the mucosa of the GI tract to help absorb.  Increse surface area.  Crypts are valleys between villi that contain glandular tissue. 
  73. Peyer's patches
    • non-glandular congregations of lymphoid tissue in the walls of the small intestine below villi.  Prominent in ileum. 
    • Control populations of bacteria
    • antibody production
    • fluid filtration.
  74. Layers of small intestine
    • Tunica serosa (outside)
    • Tunica muscularis
    • Tunica submucosa
    • Tunica mucosa
    • Lumen
  75. Bile production and track
    • Made by liver, goes through hepatic ducts to cystic duct (these together are the bile duct).  Stored in the gallbladder until goes down the bile duct into the duodenum through the major duodenal papilla. 
    • Bile breaks down and absorbs fats
  76. Bile track in equine
    • no gallbladder or cystic duct
    • constantly secreting bile through biliferous ducts into hepatic duct into duodenum. 
  77. Pancreatic duct
    • dogs and oxen have two
    • cats, horses, sheep and goats have one. 
  78. Large Intestine or Colon
    • Dehydrates fecal contents--absorbs water.  No villi, lots of lymph glands, has crypts. 
    • Cecum (blind pouch, varies with species)
    • Ascending (short in varnivore, varies with species, LOOK AT DRAWING)
    • Transverse (right to left, oten between stomach and small intestine)
    • Descending (longest part. Follows left flank, then medial to rectum)
  79. cecum
    • blind diverticulum at the beginning of the colon. 
    • Cecocolon--the one opening into the colon. 
    • Crucial fermentation center to horses.  Ileum opens into cecum in horses. 
    • Huge, comma-shaped, has a base, body and apex in the right part of the abdomen of the equine. 
    • Blind tube extending caudally in ruminants.
  80. Species differences in ascending colon
    • Carnivores: short and straight
    • Pig and ruminant: coil, the spiral colon
    • Horse: double horseshoe shaped loop (like a spiral but doubles back.  HUGE.  "Great colon"
  81. Teniae and haustra
    • bands (teniae) that pucker to form saccules (haustra) in horses and pigs.  Help tell what part of the LI you're looking at. 
    • Not in cat and dog
  82. Distal rectum
    retroperitoneal.  From descending colon to anal canal, which is the short termination of GI.  External sphincter is skeletal and voluntary. 
  83. Anal sacs
    pouches located between intermal smooth and external striated sphincter muscles of the carnivore anus.  At 4 and 8 o'clock. 
  84. Blood to intestines is supplied by
    • cranial and caudal mesenteric arteries. Collateral circulation. 
    • proximal duodenum uses shepatic branch of celiac artery
    • caudal rectum uses rectal branch of internal pudendal
    • Portal vein drains. Liver then systemic. 
    • Lots of lymph, particularly in SI, drain to thoracic duct
    • sympathetic and parasympathetic
  85. Liver
    • largest digestive gland in body.  Extramural (outside lumen of GI tract).  Caudate lobe encloses cranial right kidney. 
    • Detoxification, formation and secretion of bile, digestion of carbs, protein and fat. 
    • 6 lobes (L&R lateral, L&R medial, quadrate, caudate)
    • 2 processes (papillary, caudate)
    • 2 surfaces (diaphragmatic and visceral)
    • Dual blood supply from hepatic and portal, sympathetic and parasympathetic
  86. Lobes of the liver
    • Left lateral
    • left medial
    • quadrate
    • right medial
    • right lateral
    • caudate
  87. Processes of the liver
    • papillary: lying in the lesser curvature of the stomach
    • caudate: most caudal,  Cups the cranial pole of the right kidney in all domestics but the pig. 
  88. liver surfaces
    • diaphragmatic: convex, incontact with diaphragm. 
    • visceral: incontact with intestintes
  89. gallbladder (cholecyst)
    • between quadrate and right medial lobe of liver.  Green. 
    • Sac storing and concentrating bile.  Pours into duodenum from cystic then bile duct. 
    • Digestion and lubrication of food, break down of fats
    • Horse doesn't have one. 
  90. Falciform ligament
    attaches liver to diaphragm
  91. Pancreas
    • 2 lobes joined by a body.  Exocrine is large part secreting digestive enzymes.    Pancreatic duct exports. 
    • Fed by celiac and cranial mesenteric, drained by portal vein. 
    • Sympathetic and parasympathetic. 
    • Lies along greater curve of stomach and duodenum. 
  92. Islets of Langerhans
    endocrine part of pancreas.  Produce insulin and glucagon to help control concentration of glucose in blood. 
Card Set
Digestion lecture
test four digestion
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