Digestive System 1 Flashcards
What is the digestive system composed of?
the alimentary canal, its associated organs and exocrine glands.
organs- teeth, tongue
glands- salivary glands, liver, pancrease
What is the digestive system?
A system which includes both tubular and parenchymal organs.
- alimentary canal + all other parenchymal organs
What is the digestive tract? What is its different name?
name: ALIMENTARY CANAL
- includes only the organs in the digestive system which are tubular.
- eg. mouth, esophagus, stomach, intestine, etc.
What do all organs in the digestive tract have in common?
lumen
What does the digestive tract begin with?
lips and cheeks
What are lips and cheeks?
Folds of tissue with:
- skin on the external surface,
- mucous membrane adjacent to the oral cavity.
What is the structure of the mucous membrane in the lips and cheeks?
stratified squamous epithelium
keratinized in ruminants and horses
What is the difference between species in the lips and cheeks?
Ruminants and horses have a keratinized stratified squamous epithelium.
What does the underlying tissue of the cheeks and lips contain?
Tissue underlying the stratified squamous epithelium contains:
- serous or mixed glands
- skeletal muscle
What skin tissue lines the body? What skin tissue lines the internal surfaces of the mouth?
stratified squamous epithelium
What is the difference between the stratified squamous epithelium in different species?
the level of keratinization:
- cats and dogs eat meat (not rough food) –> does not damage the internal surface of the mouth –> not keratinized
- ruminants and horses eat rough food –> keratinized
What does the keratinization of tissue do?
gives additional protection features
What does the keratinization level of epithelium depend on?
- different species (their diets)
- individuals
Explain another reason why certain species may have keratinized epithelium in the mouth.
- adaptation reaction
- epithelium becomes keratinized to be protected from specific food.
What does the keritinization of stratified squamous epithelium depend on?
- species
- individual (adaptation reaction)
Why is the epithelium in the mouth stratified and not simple?
If the epithelium was simple, then it would be too thin, and it would get damaged every time that food was injested.
What is the thickest type of epithelium (from all epithelium classes)?
stratified squamous epithelium
What are the two types of palates?
- hard
- soft
Explain the structure of the hard palate.
- keratinized
- stratified squamous epithelium
- located on the surface with underlying connective tissue that blends with the periosteum of the palate bones.
What does the hard palate connect with?
connective tissue which blends with the periosteum of the palate bones.
What is the function of the dental pad?
It functions in place of upper incisors in ruminants.
What does the dental pad have?
Very thick keratin.
What is located further caudally in the oral cavity?
the soft palate
Explain the structure of the soft palate.
Mucous membrane fold with:
- respiratory epithelium (nasal side)
- stratified squamous epithelium (oral side)
What is special about the soft palate?
It is a fold which seperates two differerent systems:
- alimentary system (digestive tract)
- respiratory system
What is skin mobility based on?
Connective tissue beneath the epithelium.
Why is the hard palate not movable?
There is no connective tissue below the epithelium which allows for movement.
Can the dental palate be moved? Why?
Cannot be moved!
- does not have connective tissue below the epithelium
What is the dorsal epithelium of the tongue?
stratified squamous epithelium
What does the dorsal stratified squamous epithelium of the tongue vary in?
the degrees of keratinization
Explain the structure of the ventral epithelium of the tongue.
thin and non-keratinized
What is the difference between the dorsal and ventral epithelium of the tongue?
dorsal- thick and keratinized
ventral- thin and non-keratinized
What does the tongue additionally have? Where are they located?
Papillae (varous small outgrowths), located on its upper surface
What are papillae?
various small outgrowths
What do papillae vary in?
- size
- appearance
Explain a difference in size and appearance of papillae. include names!
filiform: threadlike projections or bear spines
circumvallate/fungiform: cushion shaped
foliate: take the form of a succession of folds
What do filiform papillae have unique to them?
threadlike projections or bear spines
What do circumvallate / fungiform papillae have unique to them?
cushion shape