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 glandsMandibular salivary glandsSublingual salivary glandsBuccal 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 _____________ teethMost rostral teeth

of upper and lower arcade

Canines_____________ teethLocated at corners

of incisors Longer than other

teeth Pointed at tip

Types of Teeth

Premolars_____________ teeth Rostral cheek teethSharp points and

surfacesin carnivores

Molars____________ teethCaudal 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 28Canine - adult I3/3 C1/1 P4/4 M2/3 42Feline - kitten i3/3 c1/1 p3/2 26Feline - adult I3/3 C1/1 P3/2 M1/1 30Equine - adult I3/3 C1/1 P3-4/3 M3/3 40 or 42Porcine - adult I3/3 C1/1 P4/4 M3/3 44Bovine - adult I0/3 C0/1 P3/3 M3/3 32

Dental Formulas for Several Domestic Species

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

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, lipaseCow produces 25-50 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 5.8-6.4Outside 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