Oral Cavity And Esophagus Flashcards
Layers of alimentary canal:
- Mucosa
- Submucosa
- Muscularis externa
- Serosa/Adventitia
Components of mucosa layer
- lining epithelium
- lamina propria
- muscularis mucosae
Lining epithelium type
- oral cavity and esophagus is stratified squamous
- stomach and intestine is simple columnar
Lamina propria
- loose CT
- highly cellular and contains blood-derived leukocytes important in the immune response
Muscularis mucosae
- thin layer of smooth muscle
- separates mucosa from submucosa
What does the submucosa contain?
- consists of dense CT
- contains vascular plexus that sends blood vessels into the mucosa
- Meissner’s plexus (nerve plexus)
Muscularis externa. What does it contain at the different levels?
- smooth muscle (most of alimentary canal)
- skeletal muscle (upper part of esophagus)
- mixture of smooth and skeletal (middle part of the esophagus)
Layers of muscularis externa
I. inner circular layer
II. Outer longitudinal
-nerve plexus between the two layers called the myenteric (Auerbach’s) plexus.
Serosa vs. Adventitia
Serosa- parts of the alimentary canal within the peritoneal cavity are covered with a simple squamous epithelium called mesothelioma.
-lining along with a thin underlying layer of CT
Adventitia- covers parts of the alimentary canal that are not within the peritoneal cavity
-lack simple squamous epithelium, consists of loose CT that blends into CT of surrounding structures
Layers of oral cavity?
- mucosa and submucosa
- does NOT have muscularis externa or serosa/adventitia
Mucosa of oral cavity
- does NOT have muscularis mucosae
- lining is stratified squamous epithelium
- mostly non-keratinized except, hard palate, gingiva, and some regions of tongue
Submucosa of Oral Cavity
- not clearly separated from lamina propria
- contains minor salivary glands (submucosal glands)
- Mucous-secreting branched tubular or tubuloalveolar glands.
- Minor salivary glands are intrinsic glands located in wall of oral cavity
Tissue of tongue
- covered with a stratified squamous epithelium
- often keratinized on the dorsal surface
Muscles of tongue
- skeletal muscle fibers
- has intrinsic (origin and insertion w/in tongue) and extrinsic (originate somewhere else and insert in tongue) muscles
Filiform papillae
- most abundant type in humans
- small conical projections of the keratinized epithelium and underlying CT
- do NOT contain tastebuds and have strictly a MECHANICAL ROLE
- distributed over the anterior dorsal surface of tongue with tips pointing backwards
Fungiform papillae
- mushroom-shaped projections
- more numerous toward the tip of tongue
- taste buds on APICAL surface
Circumvallate papillae
- dome shaped on the back of the tongue
- 8-12 total
- surrounded by moat like groove…epithelium lining the groove is thinner and contains numerous taste buds
Lingual salivary glands (von Ebner’s glands) and circumvallate papillae
- ducts of serous lingual salivary glands empty into the base of the groove
- serous secretion from these glands flushes material from the groove and enables taste buds to respond to changing stimuli
Foliate papillae
- formed of parallel low ridges on the lateral sides of the tongue
- histological organization is similar to circumvallate: numerous taste buds are located in grooves b/t adjacent foliate papillae, and lingual salivary glands (von Ebner’s glands) drain into these grooves
Taste buds
- oval shaped
- pale staining structures that extend the thickness of the epithelium
- taste pore is a small opening on the apical surface of taste bud
- cell types include sensory and support cells
- stimulation of taste receptors on sensory cells initiates a cascade of reactions that generates nerve impulse along the postsynaptic sensory nerve
Main role of Major Salivary Glands is the production of saliva. What are the functions of saliva?
- lubricates the oral cavity and moistens the food
- Some digestive enzymes (carbs-amylase)
- Antimicrobial-controls microbial growth within the oral cavity and caries
- contains IgA
- source of calcium and phosphate ions essential for normal tooth development
Components of Major Salivary Glands
- are extrinsic glands
1. Secretory part
2. Duct system
3. Stroma
Stroma of Major Salivary Glands
- glands surrounded by capsule of dense CT
- septa of CT extend inward from the capsule and divide the gland into lobules
- CT elements frequently contain numerous adipocytes
Serous acini of secretory part of Major Salivary Glands
- protein secreting serous cells
- cell structure: euchromatic nucleus in center of cell; basal part of cell is basophilic due to the extensive amounts of RER; the apical cytoplasm is filled with numerous, small secretory granules that stain with eosin.
- cells are pyramidal in shape..Serous acini are spherical in shape
Mucous acini of the secretory part of Major Salivary Glands
- composed of mucus secreting cells
- heterochromatic nuclei placed basally in the cell; central and apical portions of these cells are filled with mucous secretory granules that stain light with H&E
- mucous cells are columnar in shape ..so mucous acini have tubular shape
Mixed (seromucous) acini
-composed of tubular mucous component and a serous cap, or a serous demilune
Myoepithelial cells
- non-secretory cells present within the acini
- contractile cells that embrace the basal parts of the acinar secretory cells
Ductal system of salivary glands, arrangement?
- ducts within lobule are intralobular
- ducts located b/t the lobules are interlobular
- Main ducts: ducts that run from the gland to the oral cavity
2 portions of the intralobular ducts
- Intercalated ducts
2. Striated ducts
Intercalated ducts of the intralobular duct
- begin directly from the secretory acini
- lined with low cuboidal epithelium
- nucleus located near the base of the ductal cells
Striated ducts of the intralobular ducts
- connect intercalated duct s to interlobular ducts
- lined with simple columnar epithelium
- striated duct cells have numerous infoldings of the basal plasma membrane lined with numerous elongated mitochondria. *morphologic specialization is associated with active reabsorption of ions
- alter ionic composition of saliva (make saliva hypotonic by actively transporting NaCl from the saliva)
- striations fill basal part of cell so nucleus is typically in the middle or upper part of cell.
Interlobular ducts
-lined with stratified columnar epithelium
—simple columnar and stratified cuboidal epithelium can be also found within the lining of these ducts
Main ducts
-as they approach the oral cavity their lining changes to stratified squamous epithelium
Parotid salivary gland
- largest of the 3 major salivary glands
- completely SEROUS
Submandibular salivary glands
- mixed glands that contain MOSTLY SEROUS ACINI with fewer mucous acini scattered
- serous demilunes are often found in this gland
Sublingual salivary glands
- mixed glands that contain MOSTLY MUCOUS ACINI with fewer serous acini scattered among them.
- Serous demilunes are often found in this gland
Pleomorphic adenoma
- most common benign tumor
- composed of ductal and myoepithelial cells
Mucosa of esophagus
- epithelium is non-keratinized stratified squamous epithelium
- lamina propria is loose CT similar to rest of GI tract, but less cellular
- muscularis mucosae is different than stomach and intestine. It is composed of longitudinally oriented bundles of smooth muscle, separated by CT
Barrett’s esophagus
- metaplasia of the esophageal epithelium—stratified squamous epithelium to specialized intestinal columnar epithelium.
- most common of white male over 50 and GERD
- most common precursor of esophageal adenocarcinoma
Glands of esophagus location
- found within the mucosa and submucosa
- both secrete mucus to lubricate and protect the luminal wall
Mucosal glands of esophagus
-mucosal glands are called the esophageal cardiac glands and are only present in the terminal part of the esophagus and sometimes in the very beginning of it
Esophageal glands proper of esophagus
- located within the submucosa
- small compound tubuloalveolar glands scattered along the length of the esophagus
Submucosa of esophagus
- composed of dense irregular CT
- numerous blood and lymphatic vessels
- Nerve fibers and ganglion cells form Meissner’s plexus
- contain esophageal glands proper
Muscularis externa of the esophagus
- inner circular layer and outer longitudinal layer
- different than stomach and intestine b/c it contains skeletal muscle in some parts.
- Upper part composed entirely of skeletal muscle. Middle 1/3 mix of smooth and skeletal. Lower 1/3 composed entirely of smooth muscle
Adventitia of esophagus
-formed of loose CT that blends into the surrounding CT, but very distal portion of the esophagus projects into the peritoneal cavity and is covered with a serosa
