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

Peristalsis Circular muscle contractions Wavelike movement along tract ________ contents along digestive tract

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

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 SALIVARY GLANDS

Parotid salivary glands Mandibular salivary glands Sublingual salivary glands Buccal salivary glands

Teeth 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: 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

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

Carnivore Herbivore

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

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

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

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

Species Dental Formula Total Number of Teeth Canine - puppy i3/3 c1/1 p3/3 28 Canine - adultI3/3 C1/1 P4/4 M2/3 42 Feline - kitteni3/3 c1/1 p3/2 26 Feline - adultI3/3 C1/1 P3/2 M1/1 30 Equine - adultI3/3 C1/1 P3-4/3 M3/3 40 or 42 Porcine - adultI3/3 C1/1 P4/4 M3/344 Bovine - adultI0/3 C0/1 P3/3 M3/332 Dental Formulas for Several Domestic Species

Dogs: 1 st Molar in lower arcade and 4 th 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

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

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.

Functions of the Oral Cavity 1. Prehend food 2. Initiate mastication (mechanical digestion) Breaks food into smaller particles Increases surface area for chemical digestion Crushed ice melts faster than single ice cube 3. Initiate chemical digestion Saliva contains amylase, lipase Cow produces gal/d (waste basket~5 gal) 4. Prepare food for swallowing

Digestive enzymes: Proteins that promote the chemical reactions that split complex food molecules up into simpler compounds. Usually end in “ _______” ________ 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 Outside this range is damaging to necessary microbes

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