What are the lips covered by?
- Externally - integument
- Internally - mucosa
The mucosa of the lips is covered by what type of epithelium?
- Stratified squamous epithelium
- Keratinized - ruminants and horses
- Non-keratinized - carnivores and pigs
What is found in the cutaneous area of the lips but missing in the mucosa area?
- Hair follicles
- Sweat and sebaceous glands
What type of glands are usually found in the lips and where are they located?
What type of muscle is found in the tunica muscularis of the lips?
Orbicularis oris muscle
What are the layers of the tubular organs?
- Tunica mucosa (Epithelium, tunica propria, tunica muscularis)
- Tunica submucosa
- Tunica muscularis
- Tunica serosa/adventitia
What happens when lamina muscularis is absent?
Lamina propria joins with tunica submucosa to form propria-submucosa
What are the layers of the cheeks?
- Outer skin
- Middle muscular layer (buccinator muscle)
- Internal mucosa
In what animals is the mucosa of the cheeks studded with conical buccal papillae?
What are the transverse ridges on the mucosa of the hard palate?
How many incisors do ruminants have?
- They have a dental pad which consists of a heavily keratinized stratified squamous epithelium
What is the raised part of the tongue in ruminants?
What are the characteristics of the muscles of the tongue?
- Skeletal muscles
- Arranged in longitudinal, transverse and perpendicular direction
What is glossitis?
Inflammation of the tongue
What is inflammation of the oral cavity?
What is the epithelium of the tongue?
- Stratified squamous epithelium
- Keratinized on dorsal surface
- Nonkeratinized on ventral surface
What are the functions of lingual papillae?
- Mechanical - movement of ingesta
- Gustatory - contains taste buds
What type of lingual papillae is lenticular papillae?
What are the types of mechanical papillae?
Filiform, conical, lenticular
What are the types of gustatory papillae?
Which type of papillae are slender, keratinized, thread-like structures that project above the surface of the tongue and are abundant in cats and ruminants?
Which type of papillae are larger than filiform papillae and on the torus linguae of ruminants?
Which type of papillae are flattened lens-shaped projections and present on the torus linguae of ruminants?
Which papillae have taste buds on the upper surface?
Which papillae are surrounded by an epithelium lined sulcus and have taste buds on the papillary side of the sulcus?
Which type of papillae are parallel folds of the lingual mucosa with taste buds on the sides of the folds?
What are the types of cells in the taste bud?
- Sustentacular (supportive)
- Gustatory (taste receptors)
- Basal cells
What do basal cells in the taste buds do?
Replace sustentacular and gustatory cells when needed
What is a cordlike structure present in the tongue of carnivores, composed of white adipose tissue and enclosed by a dense irregular connective tissue capsule?
What is the mid-dorsal fibroelastic cord inside the tongue of the horse?
Dorsal lingual cartilage
What type of tongue do birds have?
Entoglossal tongue (bone in tongue)
What are the parts of a tooth?
- Pulp cavity
- Highly mineralized structures:
What is produced by ameloblasts?
What is enamel composed of?
- 99% mineral (hydroxyapatite)
- 1% organic matter
What is produced by odontoblasts?
What is dentine composed of?
- 70% minerals (mainly hydroxyapatite)
- 30% organic material
What forms the periodontal ligament, which anchors the tooth in the alveolus?
Bundles of collagen fibers, called cemento-alveolar (Sharpey's) fibers, extending from the alveolar bone into the cementum
Which type of teeth are short and cease to grow after eruption is completed?
What are the layers of brachydont teeth?
- Enamel - covers the crown
- Cementum - covers the root
- Dentine - thick layer beneath both the enamel and cementum
What are examples of brachydont teeth?
- All teeth of carnivores
- Incisors of ruminants
Which type of teeth are longer and continue to grow throughout life?
What are the layers of hypsodont teeth?
- Cementum and enamel cover the length of the teeth
- Cementum is outer layer
- Enamel lies on a thick layer of dentine
What is a characteristic enamel invagination in hypsodont teeth?
What are examples of hypsodont teeth?
- Cheek teeth of ruminants
- Canines of pigs and elephants
- All permanent teeth of horses
What are the major salivary glands?
- Zygomatic (carnivores)
The parotid salivary gland is predominantly ____.
What cells are present between the secretory cells and basement membranes of parotid gland?
What are the different ducts of the parotid salivary gland?
- Intercalated duct
- Striated duct
- Interlobular duct
- Main duct
What type of epithelium lines the intercalated ducts?
What are the characteristics of striated ducts?
Simple columnar epithelium with striations in the basal portions of the cells
What type of gland is the mandibular salivary gland?
- Seromucous (mixed)
- Compound tubuloacinar
What type of gland is the sublingual salivary gland?
- Compound tubuloacinar
What type of gland is the zygomatic salivary gland?
- Long branched, tubuloacinar
- Mainly mucous with flattened serous demilune
Which gland is histologically similar to the zygomatic salivary gland, located near commisure of the lips and their ducts open into oral vestibule opposite to molar teeth?
Molar salivary gland
Which animals have a molar salivary gland?
Which animal has nonkeratinized stratified squamous epithelium in the esophagus? Keratinized?
What are the minor salivary glands?
What type of glands are in the tunica submucosa of the esophagus?
In what animals is the tunica muscularis in the esophagus entirely striated? Up to two-third striated? Four-fifth of the length?
- Ruminant and dog
Which animals have a prominent cardiac sphincter?
What forms the cardiac sphincter?
Thickening of the inner circular layer of tunica muscularis at the cardia of the stomach
Where does the esophagus change from tunica adventitia to tunica serosa?
- Tunica adventitia - cervical region
- Tunica serosa - thoracic (pleura) and abdominal (peritoneum) regions
What are the four chambers of the ruminant stomach?
What is the glandular region of the ruminant's stomach?
What animal has a margoplicatus?
What separates the nonglandular region from the glandular region in the horse?
What is the epithelium of the nonglandular region of the stomach?
Stratified squamous epithelium keratinized
What lines the mucosa of the rumen?
What layer is absent in the rumen?
Lamina muscularis - forms a propria-submucosa
What is the tunica serosa of the rumen covered by?
What lines the mucosa of the reticulum?
What covers the mucosa between reticular folds and projects into the lumen?
What are the characteristics of the tunica mucosa in the reticulum?
- The lamina muscularis is absent, forming a propria-submucosa
- A band of smooth muscles is located in the upper part of the reticular fold
What extends from the cardia to the reticulo-omasal orifice, creating a bypass of the rumen and reticulum in young animals?
In the young ruminant, what contracts to create a channel allowing milk to bypass the rumen and reticulum?
Smooth muscle layers of the labia (two thick folds bordering the reticular groove)
What lines the omasal mucosa?
Omasal laminae or 'leaves' studded with macroscopic papillae
What is a characteristic of the omasum?
- Lamina muscularis is present and forms a thick layer beneath the lamina propria on both sides of the omasal leaves
- Innermost layer of the tunica muscularis is continued into the omasal laminae as the intermediate muscle sheet
What are the regions of the glandular stomach?
What are the small invaginations of the glandular stomach?
Gastric pits, which are continuous with the gastric glands
What type of epithelium lines the mucosal surface and gastric pits of the stomach?
Simple columnar epithelium
In what layer are the gastric glands densely packed?
In what animal is the cardiac gland region most developed?
What type of glands are in the cardiac gland region?
- Simple branched, coiled tubular
What are the characteristics of the gastric pits and glands of the cardiac gland region?
- Gastric pits - shallow
- Gland region - deeper
What are the parts of the fundic glands?
- Short neck
- Long body
- Slightly dilated blind end
What are the cell types that comprise the secretory epithelium of the fundic gland region?
- Mucous neck cells
- Chief (zymogen) cells
- Parietal cells
- Endocrine cells
Which are the most numerous cells of the fundic gland region?
Chief (zymogen) cells
What do the chief cells secrete?
Pepsinogen, which is transformed into pepsin by hydrochloric acid
What are the characteristics of parietal cells?
- Larger and less numberous than chief cells
- Occur singly
How do parietal cells stain?
The cytoplasm stains deeply with eosin
What do parietal cells form?
Hydrochloric acid (they contain an abundance of carbonic anhydrase)
What are endocrine cells responsible for?
Production of GIT hormones
What is used to stain endocrine cells and, thus, what are they also called?
- Silver stain
- Argentaffin cells
What are the characteristics of the gastric pits and glands of the pyloric gland region?
- Gastric pits - deeper
- Gland region - shorter
What forms the pyloric sphincter?
Middle circular layer of the tunica muscularis of the pyloric gland region
What type of cells are in the pyloric gland region?
How many layers are in the tunica muscularis of the stomach?
- 3 :
- Inner oblique
- Middle circular
- Outer longitudinal
What is the function of the lamina muscularis in the stomach?
Helps in the emptying of the glands
What makes up the tunica submucosa of tubular organs?
- Connective tissue
- Submucosal (Meissner's) plexus
What makes up the tunica muscularis of tubular organs?
- Smooth or skeletal muscles
- Myenteric (Auribach's) plexus
What specialized structures facilitate the digestive and absorptive functions of the small intestine?
- Mucosal folds - in the cranial two-thirds
- Villi - finger-like projections (only in the SI)
- Microvilli - on the free surface of the simple columnar epithelial cells
What epithelium lines the small intestine?
Simple columnar epithelium
T/F: The density of the goblet cells is greater in the caudal part of the small intestine (ileum).
What are the simple branched tubular invaginations at the base of the villi?
Crypts of Lieberkuhn (intestinal glands)
Where are crypts of Lieberkuhn located?
Small and large intestine
What lines the crypts of Lieberkuhn?
Low columnar cells, which multiply and migrate onto the villus, giving rise to the columnar and goblet cells
What cells are present near the base of the intestinal gland (crypts of Lieberkuhn) in ruminants and horses?
What are the characteristics of Paneth cells?
- Pyramid-shaped cells with prominent acidophilic granules
- Produce peptidase and lysozyme, an antibacterial compound
What other cells are present in the intestinal gland?
Enteroendocrine (argentaffin) cells
What forms the core of the villi and surrounds the intestinal glands?
T/F: The number of lymphatic nodules decreases towards the ileum.
What is located in the center of the villus, which is the origin of the lymph vessels?
What is responsible for the movement of blood and lymph?
Lamina muscularis, which extends to the tip of the villi
What is present in the tunica submucosa of the jejunum?
Nothing special, just CT, blood vessels and nerves
What is present in the tunica submucosa of the duodenum?
Brunner's glands - tubuloalveolar submucosal glands
What is present in the tunica submucosa of the ileum?
Peyer's patches - large aggregated lymphatic nodules, produce B-lymphocytes
Which animal has the thickest tunica muscularis in their small intestine?
What are special characteristics of the large intestine?
- Absence of villi
- More goblet cells
- Absence of Paneth cells
- Increase in number of lymphatic nodules
- Plicae circulares (mucosal folds) are absent but longitudinal folds are present
Where is the largest number of goblet cells?
Why is the mucosa of colon substantially thicker?
Increased length of intestinal glands
What are taenia?
Flat muscle bands containing numberous elastic fibers formed by the outer longitudinal layer of the tunica muscularis of the large intestine in pigs and horses