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
List contents of the esophagus (7)
- Esophageal glands
- Muscularis mucosae
- Submucosa
- Muscularis externa
- Adevtita
- Serosa
- Esophago/gastric junction
What are the esophageal glands? What do they contain (2)?
- mucous-secreting, tubular branched glands
a) mucosal (small number in lamina propia)
b) submucosal (widespread)
Where is the muscularis mucosa located in the esophagus?
- a few fascicles in upper esophagus
- complete thin layer in the lower esophagus
increases in thickness along the esophagus
What is located in the submucosa?
blood vessels, collagen, elastic fibers
Where is muscularis externa located in the esophagus (3)? What type of muscle composes each part?
muscularis externa (inner circular, outer longitudinal)
- upper esophagus = striated (skeletal) muscle
- middle esophagus = striated (skeletal) and smooth muscle
- lower esophagus = smooth muscle
Where is adventitia located in the esophagus?
upper and middle esophagus
Where is serosa located in the esophagus?
lower esophagus
only in lower esophagus b/c as you pass the diaphragm you now have mesothelium
What is the function of the esophago-gastric junction (2)?
- connects the esophagus to the stomach
- prevents stomach acid (reflux) from reaching the lower esophagus
What two structures protect the squamous epithelium of the esophagus from gastric acid?
- esophago-gastric junction
- esaphago-gastric muscular sphincter
What is Barrett’s esophagus?
a condition in which reflux of gastric acid damages esophageal epithelium (stratified squamous) and changes it to a gastric-type epithelium (simple columnar) =metaplasia
metaplasia = replacement of a specific cell type with another cell type not normally found in that area
What causes Barrett’s esophagus?
refulx of gastric acid secretions into the lower esophagus = heartburn
May cause inflammation and pain
What are the risk factors of Barrett’s esophagus (2)?
- Alcohol
- Smoking
What are the complications of Barrett’s esophagus?
The islands of columnar epithelium in Barrett’s esophagus are prone to:
- ulceration
- inflammation
- esophageal cancer
What are the 4 structures that make up the stomach?
- Cardia (entrance) = connects to esophagus
- Fundus = top portion
- Body = middle portion
- Pylorus (exit) = bottom → near small intestine
What are gastric rugae? What is its function?
- longitudinal fold of gastric mucosa and submucosa
- increases surface area of the stomach to allow for expansion
What type of cells are located in gastric epithelium? What is its function?
- Surface mucous cells (mucous cap)
- Fxn: secrete mucous to protect the stomach lining from digestion
What are the 5 types of cells located in gastric gland epithelium?
- Mucous neck cells
- Chief cells
- Parietal cells
- Enteroendocrine cells
- Stem cells
What is the function of mucous neck cells?
- produce soluble mucous that lubricates the gastric contents
- located near the lumen in gastric gland epithelium
exocrine secretion-released into the lumen
What are the functions of parietal cells (3)?
- produce HCL + IF (intrinsic factor)
- HCL production activated by gastrin, histamine H2 + Ach
- IF production is necessary for the absorption of vitamin B12
stains acidophilic
exocrine secretion-releases into the lumen
What is the function of chief cells?
produce pepsinogen + lipase stored in granules
stains basophilic
exocrine secretion-releases into the lumen
What are the functions of enteroendocrine cells (2)?
- produce gastrin, glucagon, serotonin, somatostatin
- releases hormones into blood = endocrine function
What is the function of stem (basal) cells?
produce and regenerate the gastric cell populations
What is H. (helicobacter) pylori?
bacteria that invades the epithelium of gastric mucosa → damages the mucosa, epithelial cells, and lamina propia = forms ulcer
What are other issues H. pylori can cause in the stomach (4)?
- chronic gastric inflammation
- ulcer
- stomach cancer
- atrophic gastritis
What is used to treat H. pylori?
antibiotics
What causes gastric ulcers?
gastric acid damages mucosa, epithelial cells, and lamina propia
Also can be caused by H. pylori and NSAIDS
How are gastric ulcers treated?
anti-ulcer drugs:
- Histamine H2 receptor blockers in the gastric mucosa (Zantac)
- Proton pump inhibitors (omeprazole) = reduce acid production
What causes Atrophic gastritis (2)? What do they damage?
- H. pylori = damages mucosal epithelium
- autoimmune disease = damage affects gastric glands of mucosa
- Can lead to pernicious anemia=damaged parietal cells cause ↓ vit B12→CNS degradation (burning sensation in soles)
Autoimmune gastritis may lead to gastric carcinoids (tumors) due to hypergastrinmeia ( ↑levels of gastrin → ↑ gastric acid)
What cells (1) secrete gastrin? Where are these cells located in the stomach?
- G cells
- located in gastric antrum (btwn. body and pylorus)
What are the 3 types of receptors parietal cells have to activate HCL secretion?
- gastrin
- histamine H2
- acetylcholine
What type of cells (1) produce histamine? Where are these cells located?
- enterochromaffin-like cells (ECL) - neuroendocrine
- located in the mucosa of gastric glands
What causes pernicious anemia?
damage to parietal cells which can decrease intrinsic factor and decrease absorption of vitamin B12
parietal cells produce intrinsic factor needed for intestinal absorption of vitamin B12 which can lead to pernicious anemia
Pernicious anemia can cause vitamin B12 deficiency. What can this lead to?
CNS degeneration (demyelination)
- e.g. subacute combined degeneration of spinal cord
- can also occur in strict vegetarians since B12 is not found in vegetables and fruits
What symptoms does pernicious anemia present?
burning sensation in soles of feet and other sensory disturbances
The muscularis externa, just before the esophago-gastric junction, is composed mainly of which type of muscle?
a. Smooth
b. Striated
c. Smooth and striated
d. Smooth and skeletal
a. Smooth
Which oral cavity structure is covered mostly by non-keratinized stratified squamous epithelium?
a. Gingiva
b. Hard palate
c. Cheek
d. Circumvallate papillae
c. Cheek
Which of the following epithelial cells, located in the gastric pits, is damaged in the case of atrophic gastritis?
a. Parietal cells
b. Chief cells
c. Enteroendocrine cells
d. Goblet cells
a. Parietal cells
Identify the following structure:
a. Oral mucosa
b. Ileum
c. Esophagus
d. Large intestine
c. Esophagus
Which of the following tongue papillae are most abundant in the oral cavity and are characterized by a lack in taste buds?
a. Fungiform
b. Filiform
c. Circumvallate
d. Foliate
b. Filiform
Identify the following cell:
a. Parietal cell
b. Paneth cell
c. Chief cell
d. Goblet cell
a. Parietal cell
Issues with the intralobular duct of the parotid gland would have what effect on the resulting saliva product?
a. Low Cl- and low HCO3-
b. Low K+/HCO3- and high Na+
c. High K+/HCO3- and low Na+
d. High HCO3- and low Cl-
b. Low K+/HCO3- and high Na+
- Intralobular duct is a continuation of striated duct, so we consider them the same
- Striated duct secrete K+/HCO3- and reabsorb Na+
What structure is #1?
palatine tonsil
What structure is #2?
epiglottis
3
lingual tonsil
4
foramen cecum
What type of papillae is #5?
circumvallate papillae
What type of papillae is #6?
foliate papillae
What type of papillae is #7?
fungiform papillae
What type of papillae is #1?
filiform papillae
What type of papillae is #2?
foliate papillae
What type of papillae is #4?
circumvallate papillae
What type of papillae is #3?
fungiform papillae
1
stellate reticulum
2
ameloblasts
3
enamel
4
dentin
5
odontoblasts
6
outer enamel epithelium
7
dental papilla
What type of gland is shown in this image?
sublingual gland
What type of gland is shown in this image?
submandibular gland
1
serous demilune
2
mucous acinus
3
serous acinus
4
intralobular ducts
1
serous demilune
2
mucous acini
3 & 4
interlobular duct
What type of gland is shown in this image?
parotid gland
dark stain
What type of cells are #1?
parietal cells
What type of cells are #2?
surface mucous cells
What type of cells are #1
chief cells
What type of cells are #2?
parietal cells
