Upper Gi Histology Flashcards
What type of muscle is found in the GI tract?
Skeletal muscle is found at either end, and smooth muscle is found throughout most of the length.
What type of nervous system is found in the GI tract?
enteric nervous system. It exists independently of the ANS.
What neurotransmitters are used in the GI tract?
Bombesin
Motilin
Vasoactive intestinal peptide
What do the endocrine cells in the GI tract secrete?
neuropeptides
What type of lymphoid tissue is found in the GI tract?
MALT (mucosal associated lymphoid tissue)
GALT (gut associated lymphoid tissue)
What is the purpose of the secretion of mucous in the GI tract?
The mucous is a lubricant and reduces friction.
You encounter a patient who has a tumor in the GI tract. Why can tumors typically be found in the GI tract?
Because the cells are highly mitotic.
What are the components of the mucous membrane?
stratified squamous epithelium
Basment membrane
Lamina propria
What three structures are derived from the epithelial bud?
enamel organ, dental papilla, dental sac (follicle)
What is the dental papilla?
A condensatio of mesenchymal cells that give rise to dentin and pulp.
What is the enamel organ?
An organ derived from the epithelial bud that forms enamel. It caps the dental papilla and dental sac, as well as forms the enamel.
The enamel organ is derived from what dermal layer?
ectoderm (under influence of mesoderm and neural crest).
The dental papilla is derived from what dermal layer?
mesoderm.
What is the function of the dental papilla?
To form dentin, cementum, and pulp as well as surrounding connetive tissue and periodontal pulp.
What is the dental lamina?
The internal limb of the labiodental lamina.
The labiodental lamina is an epithelial shelf that grows from the thickened primordium into the mesenchyme as a bifid structure.
What is the function of odontoblasts?
They form the dentrin matrix.
The also form a single layer of cells lining the pulp cavity.
They form Tomes’ detinal fibers, which are cytoplasmic extensions of odontoblast hrough predentin and dentinal layers.
What are ameloblasts?
Cells that form enamel at the tooth crown.
What are cementoblasts?
Cells that deposit cementum on the dentin of the root from neck to apex.
It has coarse collagen fibers (Sharpey’s) in a bone-like calcified matrix.
What is the histology of the peridontal membrane?
IT is connective tissue with fibroblasts, osteoblasts, cementoblasts, collagen fibers, blood vessels and nerve fibers.
What is the function of the peridontal membrane?
It binds cementum to bony socket.
It allows limited movement.
What is the sulcus terminalis?
A region that separates the anterior 2/3 of the upper oral portion from the posterior 1/3
What are the four kinds of lingual papillae?
Filliform papillae, fungiform papillae, foliate papillae, circumvallate papillae
What type of epithelium covers the lingual papillae?
stratified squamous epithelium
Which lingual papillae is the most numerous?
filiform papillae.
It lacks taste buds.
Which lingual papillae is found the least?
finguform papillae.
Where are the taste buds located on the fungiform papillae?
the oral surface of the epithelium.
Which lingual papillae is found in the tonsils?
foliate papillae
Which lingual papillae is located along the sulcus terminalis as projections surrounded by a moat?
circimvallate papillae
Ducts of von Ebner are associated which which linugal papillae?
circumvallate papillae
What is the structure of taste cells?
They are long with an elongated central nucleus. It terminates as a short taste hair which projects into the outer taste pore.
What is located at the apical region of the taste receptors?
microvilli
What occurs at the basal part of taste cells?
the release of neurotransmitters.
Taste cells can be found between what type of cells?
sustentacular cells (supporting cells).
What taste is the only one that does not use signal transduction pathways (and depolarization of the cell)?
bitter taste
What mechanisms are used to transmit salty and sour tastes?
signal transduction mechanisms.
When you eat a lemon, what channel is blocked in order to cause depolarization (and hence transmission of the taste)?
sour
What are the differences between bitter and sweet tastes?
Bitter tastes involves a hypopolarized state and sweet taste involves a hyperpolarized state.
How is the hyperpolarization of a cell achieved when something bitter is tasted?
sodium channels are blocked as the G subunit is activated and cGMP is decreased.
What are the four layers of the gut tube?
mucosa, submucosa, muscularis externa, outermost layer (serosa and adventita.)
What are the components of the mucosa?
epithelium
lamina propria
muscularis mucosa
What type of epithelium is found in the mucosa of the digestive tube?
stratified squamous transitioning to simple ccolumnar.
What is the function of the lamina propria?
It contains loose areolar CT associated with epithelium.
It also contains various glands and GALT (gut-associated lymphoid tissue).
What is the muscularis mucosa composed of?
1-3 layers of smooth muscle.
What is the submucosa?
vascularized, dense irregular connective tissue. It contains a nerve plexus: Meissner’s plexus
What is the muscularis externa composed of?
circular (inner) and longitudinal (outer) layers of smooth muscle.
What are the functions of the muscularis externa?
It regulates the size of the lumen and the rhythmic movement of the GI tract.
What are the two layers of the outermost layer of the digestive tube?
serosa and adventitia
What are the components of the serosa?
dense, irregular connective tissue. It covers intraperitoneal portions of abdominal organs.
What is the adventitia composed of?
dense irregular CT with adipose tissue.
It covers retriperitoneal portions of the digestive system.
What are the specialized regions of the esophagus?
the mucosa and muscularis externa.
What type of epithelium is the mucosa of the esophagus?
stratified squamous nonkeratinized epithelium.
What is the transition of the muscle in the musclaris extrerna of the esophagus?
There is skeletal muscle in the upper third.
There is skeletal muscle and smooth muscle in the middle third.
There is smooth muscle in the lower third.
Where does sympathetic innervation travel in the pelvis?
Through the gut wall to glands and smooth muscle.
What are the two major parasympathetic plexuses in the gut wall?
Meissner’s plexus and Auerbach’s plexus
What is the function of Meissner’s plexus?
regulates local secretions, blood flow and absorption.
What is the function of Auerbach’s plexus?
coordinates muscular activity of the gut wall.
What is the first line of defense in the gut-associated lymphoid tissue?
IgA
What is included in the diffuse lymphoid tissue in the lamina propria?
lymphocytes
macrophages
IgA secreting plasma cells.
What do aggregated lymphoid tissues form?
tonsis of the oropharynx and Peyer’s patches in the submucosa of the ileum.
What are the four regions of the stomach?
cardia, fundus, body, pylorus.
You are looking at a slide of the esophageal-stomach epithelial transition zone. The region is composed of stratified squamous epithelium and simple columnar epithelium. This region is a frequent site for what disorder?
cancer
What type of epithlium is found in the epithelial lining of the stomach?
simple columnar epithelium with mucous columnar cells.
What is found in the cardia of the stomach?
mostly mucous glands
What is found in the fundus of the stomach?
gastric glands (long tubular glands extending down to muscularis mucosae).
What is found in the body of the stomach?
gastric glands
What is found in the pylorus of the stomach?
mucous glands and hormone-secreting enteroendorcine cells.
What type of epithelium is found in the GI tract?
stratified squamous is found at the ends and simple columnar is found along most of the length.
