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Digestive Tract Musculature

Digestive Tract Musculature. Skeletal muscle - voluntary control Mouth, pharynx, cranial esophagus, ext anal sphincter Facilitates chewing, mixing saliva with food, initiation of swallowing, and control of defecation Smooth muscle

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Digestive Tract Musculature

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  1. Digestive Tract Musculature • Skeletal muscle - voluntary control • Mouth, pharynx, cranial esophagus, ext anal sphincter • Facilitates chewing, mixing saliva with food, initiation of swallowing, and control of defecation • Smooth muscle • Majority of esophagus, stomach, s. intestines, l. intestines, and internal anal sphincter • Primarily arranged in circular and longitudinal layers • Contraction of circular muscle fibers __________ tract • Contraction of longitudinal fibers __________ tract

  2. Peristalsis • Circular muscle contractions • Wavelike movement along tract • ________ contents along digestive tract

  3. Segmental Contractions • Periodic circular muscle contractions • Occur in different adjacent sites • _______ digestive tract contents and slows their movement through tract

  4. Lips, tongue, teeth, salivary glands, hard palate, soft palate, oropharynx • Lips may play role in prehension (cattle, horse) • Salivary glands - saliva helps with evaporative _________, __________, and ___________; usually three pairs with ducts to oral cavity • _________ salivary glands - ventral to ear canals • __________salivary glands - ventral to parotid glands at the caudal angle of the mandible • ____________ salivary glands - medial to the shafts of the mandible just under the base of the tongue Buccal Cavity (Mouth)

  5. Parotid salivary glands • Mandibular salivary glands • Sublingual salivary glands • Buccal salivary glands

  6. Incisors, Canines, Premolars, and Molars are found in both herbivores and carnivores • _______________ - chewing; physically break down food into smaller pieces • Increases the surface area of the food that is exposed to digestive processes • _________ arcade - in maxilla and incisive bones • _________ arcade - in mandible Teeth

  7. Teeth: Surfaces • ________ (tongue)- inner surface of lower arcade • ________ (hard palate)- inner surface of upper arcade • ________ (lips)- outer surface of upper/lower arcades (rostral) • ________ (cheek) - outer surface of teeth (caudal) • ________ – surface that grinds with other teeth

  8. Teeth: Shape • Carnivore teeth - _________ on occlusal surface; slightly curved toward back of mouth • Good for holding prey, tearing, cutting, shredding • Herbivore teeth - ________ occlusal surfaces • Good for grinding plant and grain material

  9. Carnivore Herbivore

  10. Types of Teeth • Incisors • _____________ teeth • Most rostral teeth of upper and lower arcade • Canines • _____________ teeth • Located at corners of incisors • Longer than other teeth • Pointed at tip

  11. Types of Teeth • Premolars • _____________ teeth • Rostral cheek teeth • Sharp points and surfaces in carnivores • Molars • ____________ teeth • Caudal cheek teeth • Larger, flatter occlusal surfaces

  12. Dental Formula • Typical number of each type of tooth found in upper/lower arcades • Tooth types in formula: I=incisor, C=canine, P= premolar, M=molar • __________ case: adult teeth • __________ case: deciduous teeth

  13. Dental Formula • Ruminants have no incisors or canines in their upper arcade! • _________ ______ - flat thick connective-tissue on maxilla opposite lower incisors and canines

  14. Dental Formulas for Several Domestic Species Species Dental Formula Total Number of Teeth Canine - puppy i3/3 c1/1 p3/3 28 Canine - adult I3/3 C1/1 P4/4 M2/3 42 Feline - kitten i3/3 c1/1 p3/2 26 Feline - adult I3/3 C1/1 P3/2 M1/1 30 Equine - adult I3/3 C1/1 P3-4/3 M3/3 40 or 42 Porcine - adult I3/3 C1/1 P4/4 M3/3 44 Bovine - adult I0/3 C0/1 P3/3 M3/3 32 • Tooth type followed by two numbers separated by slash mark • First number - # teeth in half of upper arcade • Second number - # teeth in half of lower arcade • Total number = sum of all numbers x 2

  15. Dogs: 1st Molar in lower arcade and 4th Premolar in upper arcade • Abscesses that form at the root of the apex of the upper carnassial tooth often break through the thin bone of the maxilla and begin to drain through the skin below the eye. • Removing the carnassial teeth is difficult due to their deeply entrenched roots Carnassial Teeth

  16. Teeth are living structures that have nerve, blood vessel and lymphatic supply, making them susceptible to damage and pain. • _____________ – tooth above gums • _____________– tooth below gums • _____________- center of tooth • Blood and nerve supply enter at apex of tooth root • ______________- surrounds and protects tooth pulp • ______________- hard conn. tissue • Covers tooth root • Fasten tooth in bony socket • ______________- covers crown • Hardest, toughest tissue in body • ______________– gums; epithelial tissue around teeth

  17. Dental Prophylaxis • Small animals- scaling away of tartar from the teeth. • Dental “__________” • Horses- teeth are “___________”, which reduces points on buccal and lingual edges of teeth.

  18. Functions of the Oral Cavity • Prehend food • Initiate mastication (mechanical digestion) • Breaks food into smaller particles • Increases surface area for chemical digestion • Crushed ice melts faster than single ice cube • Initiate chemical digestion • Saliva contains amylase, lipase • Cow produces 25-50 gal/d (waste basket~5 gal) • Prepare food for swallowing

  19. Digestive enzymes: • Proteins that promote the chemical reactions that split complex food molecules up into simpler compounds. • Usually end in “ _______” • Secreted in the digestive system to break down different components of food. • ________ • Found in saliva of omnivores but absent in carnivores • Breaks down amylose- a sugar component of starch. • ________ • Digests lipids • Found in saliva of young animals while nursing or on high milk diet. • Buffers: • Sodium bicarbonate and phosphate buffers found in saliva of cattle • Neutralize acids normally formed in rumen • Monogastric stomach pH~2-3 • Ideal rumen pH 5.8-6.4 • Outside this range is damaging to necessary microbes

  20. Nervous System and Salivation • Autonomic nervous system controls most digestive glands • Parasympathetic ___________ salivation • Anticipation of eating stimulates salivation (Pavlov) • Sympathetic_____________ salivation and activity of other digestive organs • Fear produces produce dry mouth

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