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Histology- GI tract


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What are APUD's?
Amine Precursor Uptake and Decarboxylation cells.

"Enteroendocrine" cells: produce and secrete hormones

Where can you find taste buds?
1) Fungiform, Circumvallate papillae
2) Palate
3) Palatoglossal Arch
4) Palatopharyngeal Arch
5) Pharynx and Larynx
What is a lacteal?
It is a blind ended lymphatic within the villi of the small intestine.
What are the von Ebner glands?
These are serous glands that open into the trenches around the cicumvallate papillae.
What types of hormones do APUD's secrete?
1) Gastrin
2) Secretin
3) Cholecystokinin
4) Somatostatin
Why are filiform papillae different?
1) Smallest and most numerous
2) Provide tongue with rough surface for food manipulation
3) Cone like
Describe the intestinal glands of the small intestine:
1) Simple
2) Straight
3) Tubular
4) Penetrate to the level of the Muscularis mucosa
What are the fungiform papillae?
1) Occur in anterior 2/3
2) Loners and evenly spaced between filiform papillae
3) CT core is highly vascularized
4) Epithelium slightly thinner than the rest of tongue
How can you tell the pyloric region of the stomach?
Villi: NO
Glands: Short Coiled
Parietal and chief cells: NO
Pits: Long
What types of muscles are in the tongue?
Skeletal musc. arranged more or less perpendicular to each other.
How is the Small intestine divided?
1) Duodenum (Brunner's glands)
2) Jejunum
3) Ileum
In general, what are the ingredients of the lingual papillae?
1) connective tissue core
2) Stratified squamous epithelium
What are Chief Cells?
1) Lower half of gastric gland
2) Pepsinogen (becomes active as pH goes down)
How is the dorsal surface of the tongue is divided?
It is divided by the sulcus terminalis

1) anterior 2/3 (Oral part)
2) posterior 1/3 (Pharyngeal part)
Describe the changes in villi through the course of the small intestine:
1) Duodenum: Short, leaf shaped plates
2) Jejunum: Club shaped
3) Ileum: Finger shaped and tall

They all contain rich supply of vessels, lacteals, and SM
Describe the epithelium of the DORSAL side of the tongue
Epithelium: stratified squamous
CT: Very dense and connects the epithelium to the underlying muscle
What are the cells that you will find in the gastric pits of the Body and Fundus?
1) Parietal
2) Chief
3) Mucous neck cells
4) Enterochrimaffin cells
5) APUD's
What can you find on the oral part of the tongue?
Large number of papillae
1) Filiform
2) Fungiform
3) Circumvilate
4) Foliate
What do you find in the Lamina propria of the intestine?
1) CT
2) Vascular elements
3) diffuse and nodular LYMPHOID TISSUE
4) Muscularis mucosa (inner: circ :: outer: long)
Where to the circumvallate pap. appear?
1) In depressions of the surface of the tongue
2) Surrounded by trench formed by in folded epi
How many layers does the muscularic mucosa have in the stomach?
2 to 3 layers of smooth muscle that creeps up between glands
What are the circumvallate papillae?
1) Largest least numerous
2) 8-12 of them
3) Taste buds line the walls
4) Glands of Von Ebner open into trenches
What types of cells do you find in the mucosa of the small intestine?
1) Simple Columnar
2) Goblet Cells-> Mucous
3) Paneth Cells-> bottom of crypts
4) Argentaffin and APUD cells (basal section of glands)
5) Lamina Propria
What are Argentaffin Cells?
1) Enterochromaffin cells
2) Derived from neural crest cells
3) Basal portions of the glands
How does the small intestine increase its surface area? (6)
1) Villi
2) Extreme length
3) Plicae Circulares
4) Intestinal Glands
5) Microvilli on apical surface of absorptive cells
6) Glycocalyx
How can you determine the Body and Fundus?
Villi: NO
Glands: Coiled
Parietal and Chief cells: YES
What are brunner's glands?
Submucosal duodenal glands that produce an ALKALINE secretion to protect wall from low pH.

Sets optimal pH for pancreatic enzymes
What are some of the gross anatomical features of the stomach?
1) Rugae (longitudinal folds that change in distention)
2) Cardiac Region
3) Fundic/Body region
4) Pyloric region
What makes the duodenum different?
Villi: YES
Submusocal glands: YES (brunner's)
Esophagus: Muscle Layer
1) Two layers of Muscle
2) Top 1/3 is wrapped in skeletal muscle
3) Middle is combination
4) Bottom 1/3 is all smooth muscle
What does the inner layer of the Muscularis mucosa of the small intestine do?
Sends fibers into the villi that contract every 10 seconds
How can you tell the cardiac region?
Villi: NO
Glands: Coiled and long
Parietal and Chief cells: NO
Pits: Short
How can you identify the Ileum?
Villi: YES (Farther apart)
Submucosal Glands: NO
Plicae Circulares: YES (but less)
Peyers Patches: YES
Goblet cells: Increase
What are parietal cells?
1) HCL
2) Vit B12 intrinsic factor
3) Middle portion of gastric glands with mucous neck cells
4) Have Mitochondria for ATP pumps
5) Triangular in Shape
How can you tell the Large Intestine?
Villi: NO
Goblet cells: YES!!! (Lots)
Mucosal glands: Tubular
Lymphoid Tissue: Nodules
Outer layer: Tenia Coli
What types of cells do you find in Gastric Pits?
1) Stem Cells
2) Mucous Neck Cells
3) Parietal cells
4) Chief cells
5) Enteroendocrine cells
How can you identify the Jejunum?
Villi: YES
Submucosal Glands: NO
Plicae Circulares: YES
Peyers Patches: NO
Goblet cells: Some
Esophagus: Outer Layer
1) Thoracic portion is covered in adventitia (CT)
2) Sub-diaphragm is wrapped in serosa
What is the muscularis mucosa like in the esophagus?
VERY THICK (Generally m.m. is thin)
Describe the mucosa of the esophagus
1) Lined with stratified squamous epithelium
2) Lamina propria
3) relatively thick muscularis mucosa
4) Cardiac glands that secrete mucous near the stomach
What do you find in the Submucosa?
1) Layer of CT with blood and lymph vessels
2) Meissner's plexus for contraction
3) Submucosal Glands (Esophagus and duodenum)
Esophagus : Submucosal layer
1) "Esophageal" glands
2) Relatively thick fibroelastic layer that stretches as you swallow
What is in the Lamina Propria?
1) Areolar CT
2) Blood vessels
3) Nerves
4) Smooth muscle
5) Glands
What are mucous neck cells?
1) Mucous
2) Occur singly or in clusters between parietal cells
3) Upper half of Gastric glands
How does a taste bud work?
1) Pieces of food are sampled in the trenches
2) Sensory cells extend microvilli into taste pore.
3) There are receptors on the microvilli with different taste modalities
Describe the Muscle layer of the general GI.
1) relatively thick
2) Composed of SM into 2 layers (inner: circular :: outer: Longitudinal)
3) Auerbach's plexus between the layers of muscle
Describe the mucosa of the gut
1) Faces the lumen
2) Epithelial lining
3) Lamina Propria
4) Muscularis mucosa
Segmentalize the esophagus:
1) First third contains Skeletal muscle
2) Mixture
3) Smooth muscle
What is a serosa?
The combination of adventitia (CT) and mesothelium (s.s. epi)

Contains: blood vessels, lymphatics, nerves, and adipose tissue
Where do you find a serosa?
The outer most layer of the gut. All over the gut, except in the eophagus
What is the general plan of the Digestive tract?
1) Mucosa
2) Submucosa
3) Muscle Layer
4) Serosa or adventitia

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