Lecture 1: Digestive I Flashcards
What are the 2 types of epithelium that line the oral cavity of the GI tract?
- Kertanized stratified squamous
- Nonkeratanized stratified squamous
Which structures in the oral cavity are lined with keratinized stratified squamous (rough surfaces) (3)?
- gingiva - gums
- hard palate = roof of the mouth
- dorsal surface of the tongue
Which structures in the oral cavity are lined with nonkeratinized stratified squamous (smooth surfaces) (3)?
- ventral surface of the tongue
- floor of the mouth
- mucosal surface of the lips and cheeks
What are papillae and where are they located on the tongue?
Mucosal elevations on the anterior, dorsal surface of the tongue
What is the shape of filiform papillae?
long thread-like shape or feather-like shaped
What is the shape of fungiform papillae?
mushroom-shaped projections
What is the shape of circumvallate papillae?
dome-shaped
Where in the oral cavity can taste buds be found? (5)?
- fungiform papillae
- circumvallate papillae
- foliate papillae
- oral mucosa
- pharyngeal mucosa
What are foliate papillae?
small lateral folds of the mucosa
groups of peaks
Which papillae is the most abundant?
filiform papillae
Which papillae is the only one that does not have taste buds?
filiform papillae
What are the 3 principal cell types of the tongue?
- neuroepithelial cells
- supporting cells
- basal cells
What are the 5 taste stimuli of the tongue?
- sweet
- salty
- bitter
- acid
- umami
Taste information reaches the cerebral cortex through which 3 nerves?
- Primarily through the facial (VII) and glossopharyngeal (IX) nerves
- Some taste information through the vagus nerve (X)
Where are sensory neurons synapse in the medulla located?
solitary nucleus
What are the functions of the oral mucosa (2)?
- forms a protective barrier → epithelium, migratory neutrophils, saliva
- resistant to entering pathogens and indigenous microbial flora
What are the protective mechanisms of the oral mucosa (4)?
- Saliva = salivary antimicrobial peptides
- Epithelium = beta-defensins expression
- Neutrophils = alpha-defensins expression
- Plasma cells = immunoglobulin A secretion into saliva (plasma cells located in the connective tissue near the secretory acini)
What are the 7 components that make up the tooth?
- Enamel
- Dentin
- Cementum (cellular and acellular)
- Periodontal ligament
- Gingiva
- Aveolar process (bone)
- Dental pulp
What 4 components make up enamel?
- amelogengin
- enamelin
- hydroxyapatite crystals
- ameloblasts
Amleoblasts are present only in developing “baby” teeth
What 3 components make up dentin?
- predentin (type I collagen, glycosaminoglycans)
- hydroxyapatite crystals
- odontoblasts
What is saliva made of (5)?
- ⍺-amylase
- lysozyme
- secretory IgA
- Water
- bicarbonate ion
“Salivating Amy Likes Intense Weed Brownies”
What are the minor salivary glands (2)? Where are they located?
- liguinal, palatine
- located in the submucosa of the oral cavity
have short ducts which empty directly to the oral cavity
What type of glands are formed when epithelial cells maintain contact with the surface of CT?
exocrine glands
What type of glands form when epithelial cells do NOT maintain contact with the surface of CT?
endocrine glands
What are the 3 types of secretions exocrine glands have?
- Mucous → viscous, slimy, glycosylated proteins, water-soluble, lost during tissue preparation
- Serous → watery: non-glycosylated proteins, secretory granules well preserved , basophilic rER
- Mixed
What are the 3 major salivary glands?
- Parotid
- Submandibular
- Sublingual
What type of secretion does the parotid gland excrete?
All serous (dark stain)
What type of secretion does the submandibular gland excrete?
Mixed, mostly serous + some mucous (slightly dark stain)
What type of secretion does the sublingual gland excrete?
Mostly mucous (light stain)
some serous
What are the 3 ducts of the major salivary glands? Where are they located?
- Intercalated duct = in serous and mixed glands
- Striated duct = in serous glands
- Excretory duct = interlobular and interlobar
List the order of the duct system (flow of saliva) (6)
- Acinus
- Intercalated duct
- Striated duct
- InTRAlobular duct
- InTERlobular duct
- Main duct
What is the function of the Acinus?
- Secrete initial saliva product
- Are terminal sacs the produce saliva→myoepithelial cells push saliva out and into intercalated disks
What are the functions of the intercalated duct (3)? What type of epithelium does it have?
- Secrete bicarbonate ion (HCO3-)
- Absorb Chloride ion (Cl-)
- Several ducts merge to form striated duct
- Simple squamous
What are the functions of the striated duct (3)? What type of epithelium does it have?
- secrete potassium (K+) and HCO3- to the secretion
- reabsorb sodium ion (Na+) from the primary secretion
- several ducts merge to form the intralobular duct
- Cubodial/short columnar
What is the intralobular duct? What type of epithelium does it have?
Low yield
- Striations in the basement membrane, ducts from each lobe merge to form interlobular ducts
- Continuation of striated duct, so we consider them the same
- Cuboidal-columnar
What is the type of epithelium is found in the interlobular duct?
Low yield
Pseudostratified columnar
What is the function of the main duct?
Low yield
Secrete saliva directly into the oral cavity
What is the function of excretory duct?
passage of secretion
How does the parotid gland become infected with mumps?
virus transmitted through saliva
What does mumps cause?
Parotid gland to swell which can cause damage to facial nerve (CN VII)
What are the complications of mumps?
- sterility
- meningitis
What does a benign salivary gland tumor cause?
numbness or weakness of innervated muscle due to nerve involvement
How is a benign salivary gland tumor treated?
Excision of parotid gland may be necessary – risk of damaging facial nerve
What glands does Sjogren Syndrome affect?
ALL of the salivary glands
What are the symptoms of Sjogren Syndrome (3)?
- dry mouth
- dry eyes
- enlarged salivary glands with lymphocyte infiltrations
What is Sjogren Syndrome? What causes it?
- Autoimmune disease
- caused by CD4+ cell reaction against unknown antigen in the ductal epithelial cells of the exocrine glands.
What are the layers of the GI tract (alimentary canal) from internal to external (4)? What type of epithelium or CT does each have?
- Mucosa = epithelium → lamina propia (loose CT) → muscularis mucosa (2 layers of SM)
- Submucosae/submucosa = dense irregular CT
- Muscularis Externa = outer longitudinal + inner circular layer of SM
- Adventitia = loose CT or Serosa = mesothelium + loose CT
What type of epithelium lines the esophagus?
stratified squamous epithelium