Upper Alimentary Tract (DeMonaco)

Question 1

What is the upper alimentary tract

Answer 1

oral cavity, pharynx, esophagus -> connect down to stomach

Where nutrients are taken into the body

Question 2

Food prehension

Answer 2

how an animal takes up food
- dog, cat = teeth
- horse = lips
- pig = nose, lower lip, tongue
- cattle = tongue
- small ruminants = lips & tongue

Question 3

Dog/cat water ingestion method vs horse/ruminant/pigs

Answer 3

Dogs & cats: lap water up w/ tongue
Horses/ruminants/pigs: siphon water up by pursing their lips & creating negative pressure // suction

Question 4

What occurs during mastication (chewing)?

Answer 4

Food is divided and mixed with saliva secreted by the salivary glands

Saliva: water, electrolytes, mucin, antibacterial compounds, enzymes

Question 5

Where does digestion begin?

Answer 5

in the oral cavity (mechanically)

Question 6

Deglutition (swallowing)

Answer 6

moves the bolus of food/water from mouth -> stomach

swallowing = voluntary, everything after = reflexive

receptors in pharynx stimualte medullary swallowing centers; from here on through, ALL REFLEXIVE

Question 7

3 phases of deglutition (swallowing)

Answer 7

1. Oropharyngeal
2. Esophageal
3. Gastroesophageal

Question 8

UES and LES + functions

Answer 8

Upper Esophageal Sphincter
- high-pressure zone at the transition of the pharynx and the cervical esophagus
- prevents retrograde movement (prevents airentry into esophagus during breathing, and prevents reflux into pharynx during swallowing)

Lower Esophageal Sphincter
- high-pressure zone located where the esophagus meets the stomach and protects the esophagus from the reflux of gastric contents

Question 9

Submucosal mucous glands of the esophagus function

Answer 9

secrete mucus that facilitates swallowing

Question 10

Muscle variations of esophagus
- dogs/ruminants
- cats/horses

Answer 10

• dogs/ruminants = all skeletal m.
• cats/horses = cranial 2/3 skeletal m., distal 1/3 smooth m.

dogs get myasthenia gravis (lack Ach) more than cats b/c all skeletal m.

Question 11

What initiates primary peristalsis and secondary peristalsis

Answer 11

Differ only by stimulus:
1. 1º. = swallowing
2. 2º = food bolus “stuck” in lumen of esophagus

both have goal of moving food bolus into stomach

Stimulated by acetylcholine

contractions of musculature behind food bolus + esophagus dilates ahead of it

Question 12

Dysfunction of the UES can cause what

Answer 12

Dysphagia

see repeated attempts at swallowing; regurg