ANSC 2202 - Proximal Gastrointestinal System

Mouth to stomach

3 Body Cavities and what/where are they?

• Thoracic cavity

• Abdominal cavity

  • Thoracic and abdominal are divided by the diaphragm

• Pelvic cavity

What is part of the oral cavity?

• Lips

• Cheeks

• Tongue

• Teeth

• Hard and soft palete

Lips

• Very sensitive and mobile

• Whiskers help with navigation, finding food, etc; tactile

Prehension

• The act of grasping food with the mouth

Hard Palate

• The upper roof of the mouth

  • Rostral portion of the palate

  • Contains palatine ridges

Palatine Ridges

• Ridge-like structures across the hard palate

  • Also called rugal folds

Soft Palate

• The back of the mouth

  • Caudal portion of the palate

• Composed of soft tissues—NO BONE

The Tongue

• Strongest muscle in the body

• Made of 4+ muscles and controlled by 4 nerves

• Used to orient grass/manipulate food

• Latin word: Lingua

Frenulum Linguae

• A fold of tissue that attaches the tongue to the floor of the mouth

Torus Linguae

• A bulging of the caudodorsal surface of the tongue 

  • Aids in rumination (cud) and mastication

Lingual Fossa

• Depression in front of the torus linguae

Salivary Glands

• Exocrine glands located outside of the digestive tract

  • Secrete saliva into the mouth via ducts

  • Accessory to the digestive system

Parotid Gland

• Serous (clear, watery) secretions

• Largest in herbivores

  • Aligning the jaw

  • Base of the ear

Mandibular Gland

• Serous/mucous (thick, sticky) secretions

  • At ramus (angle of the jaw) of mandible

Sublingual Gland

• Serous/mucous secretions

  • Under the tongue

How much saliva do cows produce daily?

• 10-45 gallons

Pharynx

• Common passageway leading from the oral and nasal passages to the esophagus and larynx

  • Larnyx - “voice box”

Esophagus

• Carries food from the mouth to the stomach

  • Opening is dorsal to the larynx

• Secretes some mucus

• Food is moved toward the stomach via peristalis

Peristalis

• A wave-like movement of muscles that moves food through the digestive system

Omentum

• Web-like tissue that attaches the stomach to the body wall or other organs

Stomach

• Storage

• Mixing of food with gastric enzymes

• Starts mechanical (peristalsis) and chemical breakdown of food

• No nutrients are absorbed in the stomach

Stomach Lining (glandular or not between species)

• Carnivores:

  • Glandular (has digestive glands)

• Ruminants, Horses, Pigs:

  • Composite

    • Glandular and non-glandular (lacks digestive glands)

Types of Stomachs

• Simple

  • Monogastric = humans, carnivores, horses, pigs

    • “One Stomach”

• Complex

  • Often 4 compartment stomachs

  • Ruminants

    • Allows for digestion of plant-based diet

Cardia

• Opening into the stomach in which the esophagus is attached

Fundus

• Left side of the stomach adjacent to the cardia often expanded with gas

Pylorus

• Distal portion of the stomach; connects to the duodenum

  • Contains a very obvious dividing line between the body and the pylorus of the stomach

Gastric Diverticulum

• In pigs only

• Conical extension of the fundus

Complex Stomach Compartments (4)

• Rumen

  • Largest, fermentation vat, rug-like

• Reticulum

  • honeycomb, most ventral

• Omasum

  • Akin to book pages, “butchers bible,” absorbs water

• Abomasum

  • “True stomach” - glandular

Cows have 4 stomachs

• FALSE

  • Cows have 1 stomach with 4 compartments

Gastric Groove

• Tube from cardia to abomasum in neonates (newborns)

  • Allows milk to bypass the first 3 compartments

  • Closed in adults

Torus Pyloricus

• Small lump of tissue by the pyloris

  • Found in pigs and ruminants

What is hardware disease and what can it be prevented with?

• Caused when ruminants swallow non-digestible matter (screws, wire, etc)

• It can be prevented by placing a magnet in the ruminant’s reticulum, where it will remain throughout life