EXAM III Upper GI Flashcards
What type of epithelium is along the length of the upper GI and at both ends?
Lengthwise = Simple columnar w/ glands
Both ends = Stratified squamous
What type of muscle is along the length of the upper GI and at both ends?
Lengthwise = smooth muscle
Both ends = skeletal muscle
Describe the mucous membrane lining the oral cavity
Lined with a mucous membrane lying on a vascular FECT layer
Mucosa = stratified squamous (poorly keratinized), basement membrane, lamina propria w/ high papillae and mixed mucous glands
Dermis = rich plexus of capillaries prominent at free margin of lip
Altho the cheek has a similar structure to the lip, what is one exception?
Contain abundant elastic fibers present in submucosa continuous w/ fibers surrounding striated muscle and lamina propria = max distensibility to oral mucous membrane
What are the components of the oral cavity?
Teeth
Tongue (w/ taste buds)
What 3 embryonic tissues interact in the developing teeth?
MEN (some men have beautiful teeth)
Mesoderm
Ectoderm = forms enamel organ
Formed under influence of mesoderm & neural crest
Neural crest
M & E form dental papilla, dentin, cementum (holds tooth into alveolar/tooth socket), pulp, & surrounding CT and periodontal pulp
What is the dental lamina (teeth)?
The internal limb of the labiodental lamina that grows from the primordium into the mesenchyme bifid structure.
primordium = fromed from basal cells of oral ectoderm
bifid = (labiodental lamina) external limb splits later to form groove that separates lip and rest of mouth
What 3 cells are involved in the development of teeth?
ACO Always Cum Orally
Ameloblasts
Cementoblasts
Odontoblasts
Describe the histology and function of the Ameloblasts
Forms the enamel (only covers tooth crown)
Enamel - hardest substance in body (96% inorganic salts, 90% is CaPhosphate = apatite crystals & 4% organic matter)
Laid down in prisms, formed by a single ameloblast
Tomes’ processes = apical domains
Periods of rhythmic growth = Increment lines of Retzius
No collagen and NOT regenerated (hence cavities)
Describe the histology and function of the Cementoblasts
Sharpey’s fibers
in a bone-like calcified matrix
Deposit cementum on dentin of the root from neck to apex
Cementum = cells of dental sac that differentiate into cementoblasts which do above ^
a thin layer of bony material that fixes teeth to the jaw.
Describe the histology and function of Odontoblasts
Matrix = 20% organic bone material & Type I collagen
Forms dentin matrix thruout tooth’s life (as opposed to Ameloblasts which is not regerated)
Forms single layer of cells lining pulp cavity
Tomes’ dentinal fibers - cytoplasmic extensions of odontoblasts
Increment lines of Ebner and Owen (growth spurts)
What 2 organic components are unique to enamel and removed after calcification?
A&E Apples & Ecstasy
Amelogenins
Enamelins
What does the pulp consist of, where is it derived from?
Dental papilla via epithelial bud
Fibroblasts, MOs, peripheral odontoblasts, reticular fibers, nerve fibers, blood vessels that pass via apical foramen
Pulp = part in the center of a tooth made up of living connective tissue and odontoblasts
Describe the histology and functions of the periodontal membrane
Connective tissue formed from dental sac w/ fibroblasts, osteoblasts, cementoblasts, collagen fibers, blood vessels, and nerve fibers
Highly metabolic
Binds cementum to bony socket
Sharpey’s fibers extend from cementum to alveolar wall via membrane
Absorbs pressures of mastication & prevents pressure from damaging alveolar bone
Affected by diseases; diabetes & scurvy
What is the sulcus terminalis?
Separates the anterior 2/3 of upper oral portion from the posterior 1/3
What are the 4 kinds of lingual papillae?
CFFF Come Fk Friends on Friday (tgif)
Circumvallate papillae
Filliform papillae
Foliate papillae
Fungiform papillae
Define lingual papillae
Surface projections (not taste buds)
Locations and characteristics of the filiform papillae?
Most numerous w/ a conical appearance
Evenly distributed over upper oral portion
Lack taste buds
Locations and characteristics of the fungiform papillae?
Relatively few
Interspersed singly among parallel rows of filiform papillae
Mushroom appearance
Taste buds present on oral surface only compared to circumvallate papillae whose taste buds are on lateral walls
Locations and characteristics of the foliate papillae?
Rudimentary in humans; well developed in lower animals
Pharyngeal portion is free of papillae, contains lingual tonsils
Locations and characteristics of the circumvallate papillae?
Along sulcus terminalis as projections surrounded by a moat (circular furrow)
Taste buds on lateral walls
Ducts of von Ebner’s glands (serous) open into the moat
What 2 cells are derived from taste buds?
S.T. - Taste Spectacullarly
Sustentacular cells
Taste cells
Derived from a single stem cell
Describe structure of sustentacular cells
Spindle-shaped support cells
Arranged like barrel-staves to surround inner taste pore at the base
Describe structure of taste cells
“The type of woman that you want to taste” ;) But she gives you a short taste…
Long & Slender w/ elongated central nucleus
Terminates as a short taste hair that projects into the outer taste pore
Apical microvilli w/ taste receptors
Basal portion releases NTs
Distributed b/w sustentacular cells
How does taste sensation take into affect? (besides bitterness)
Via signal transductions pathways = depolarization of taste cell
How does bitter taste come into affect? Sweet taste?
“Bitter and Low”
Hypopolarized state similar to retinal cell signal transduction
Sweet taste = hyperpolarized state
What are the 4 layers of the gut tube?
M.S.M.S&A. = Many Solo Mothers Stay Angry (Chayla!)
Mucosa
Submucosa
Muscularis externa
Serosa and Adventitia
Describe mucosa of the gut tube (innermost)
Epithelium
Lamina propria
Muscularis mucosa
Stratified squamous transitioning to simple columnar
L.P. = loose areolar CT associated w/ epi.
contains glands and GALT
M.M. = 1-3 non-distinguishable smooth muscle layers
Decribe the submucosa of the gut tube
Nerve plexus?
Dense, irregular CT
Vascularized
Meissner’s plexus (submucosal plexus)
Describe the muscularis externa layer of the gut tube
Nerve plexus
Functions
Inner circular layer of smooth muscle
Outer longitudinal layer of smooth muscle
Myenteric/Auerbach’s nerve plexus b/w the two muscle tissue layers
Regulates lumen size via circular layer
Regulates rhythmic movement of GI tract via longitudinal layer
Describe the serosa and adventitia of the gut tube
Serosa - dense irregular CT
Mesothlial lining & layer of submesothelial CT
Forms visceral peritoneum
Covers intraperitoneal portions of abdominal organs
Adventitia - dense irregular CT w/ adipose tissue
Covers retroperitoneal portions of digestive system
Although serosa and adventita are both components of the outermost layer of the gut tube, what is a distinct characteristic between the two?
Serosa covers INTRAperitoneal portions of abdominal organs
Adventitia covers RETROperitoneal portions of the digestive system
Where is the Meissner’s plexus located and what is its function?
Submucosa layer of the gut tube
Regulates local secretions, blood flow, and absorption
Where is the Auebachs/Myenteric nerve plexus located and what is its function?
Muscularis externa layer of the gut tube b/w the circular and longitudinal layers
Coordinates muscular activity of gut wall (lumen size & rhythmic movement)
Describe the gut-associated lymphoid tissue, what immunoglobulin is associated with it? What components are within the lamina propria?
IgA found coating the luminal surface of the mucosal epithelium
L.P. = isolated lymph follicles retrieve food Ags from M/mucosal cells (specialized squamous epi. cells)
IgA secreted by Ag-stimulated B cells in follicles
Diffuse lymphoid tissue = lymphocytes, MOs, IgA-secreting plasma cells
Aggregated lymphoid follicles = form tonsils of the oropharynx (Waldeyer’s ring) & Peyer’s patches in submucosa of ileum
What is the function of the esophagus?
Digestion
Addition of mucous to food bolus
What structural specializations does the esophagus possess? (in 2 locations)
Mucosa - stratified squamous nonkeratinized epi. in lamina propria and submucosa
Muscularis externa - transitions from skeletal muscle only (upper 3rd) –> to skeletal/smooth muscle (middle 3rd) –> smooth muscle only (lower 3rd)
Frequent spot for cancer!!!
What are the 4 regions of the stomach?
C.F.B.P. Chayla Fks Basic People
Cardia
Fundus
Body
Pylorus
Location and characteristics of Cardia of the stomach?
C.F.B.P.
Most proximal region
Contains mostly mucous glands
Characteristics and components of fundus of the stomach?
Contains Gastric glands
Long tubular glands extending down to muscularis mucosae
Composed of mucous neck cells, parietal cells, chief cells, stem cells, and enteroendocrine cells
Characteristics of body of the stomach?
Contains Gastric glands; same as fundus
Long tubular glands extending down to muscularis mucosae
Composed of mucous neck cells, parietal cells, chief cells, stem cells, and enteroendocrine cells
Contents of the Pylorus of the stomach?
Mucous glands
Hormones-secreting enteroendocrine cells
Pyloric glands - simple tubular, branched at very low end towards muscularis mucosa
Describe the epithelium of the stomach
Gastric mucosa = simple columnar epi. w/ mucous columnar cells (goblet cells)
Suface mucous cells secrete a protective insoluble mucous (to avoid stomach 4rm being digested)
Contain Rugae = longitudinal mucosal folds most prominent in an empty stomach
Describe the gastric glands and muscularis externa of the stomach
Glands = open into the gastric pits
Muscularis = 3 layers of smooth muscles; 3rd = inner oblique layer
Describe the overall characteristics of gastric glands
Simple branched tubular glands
Narrow isthmus opens into bottom of gastric pit
Fundus/base of gland extends into lamina propria
What are the 5 cell types of the gastric gland?
SCEMP
Stomachs Can Eat Multiple Parasites/People
Stem Cells - replace cells of gastric pit
Chieft Cells - secrete pepsinogen
Enteroendocrine Cells (APUD cells)
Mucous Neck Cells - secrete soluble mucous
Parietal Cells/Oxyntic Cells - HCl, Intrinsic factor
Describe the structure and function of parietal cells of the gastric gland
Large, pyramidal shaped, eosinophilic cell
Produces HCl and gastric intrinsic factor
Generates H+ from CA
Prominent intracellular canaliculi lined by microvilli
Have lighter appearance than chief cells on micrograph
What is the function of chief cells of gastric glands?
Secrete pepsinogen
Zymogenic cells; produce zymogen granules
Have a darker appearance than parietal cells on micrographs
What is the function of enteroendocrine cells of the gastric gland?
APUD Cells = amine precursor uptake & decarboxylation cells
Produce peptide hormones and serotonin
Small cells w/ secretory vesicles polarized toward basal surface in proximity to blood vessels
List the major structural features that increase surface area for absorption in the GI tract (3); Three Orders of Folding
You da real MVP GI!
Microvilli
Villi (Crypt-Villi system)
Plicae circulares (valves of Kerckring; poles in the mucosa)
Describe the histology of the crypt-villus system
Each villus has a core of lamina propria
Crypts extend down b/w villi below the bases of the villi
Crypts & villi constitute glands of small intestine
Each villus = capillary plexus, blind-eating lymphatic = lacteal
Wall of villus = simple columnar epi. w/ goblet cells
Define plicae
Folds of the mucosa
Each containing a submucosal core
Describe the fine structure of the microvilli
glycolipid coat = glycoprotein and glycocalyx
Bundles of actin filaments within microvillus covered by a formin cap
Supported by core of actin microfilaments
Actin filaments are tied to terminal web intermediate filaments via spectrin fibrils
Actin filaments are bound to plasma membrane covering villus via membrane-linking proteins (Myosin I and calmodulin)
Actin filaments are bound to each other via actin cross-linking proteins (Villin and fimbrin)
Describe the glycocalyx
An array of brush border enzymes that are produced by small intestinal epithelial cells
Maltase
Isomaltase
Sucrase
Lactase
Lipase
Peptidase
