Histology - Gastrointestinal Block Flashcards
What type(s) of epithelia is(are) found in the oral cavity?
(1) Non-keratinized stratified squamous (lining mucosa)
(2) Keratinized or para-keratinized stratified squamous (lining gingiva and hard palate)
(3) Specialized papillae and taste buds (dorsal tongue)
What are the three histological sections of the oral lip?
Describe each.
(1) Cutaneous, (2) vermillion/red, (3) oral mucosa
What muscle group is found in the lips?
Orbicularis oris
Name the histological lip region described: thin skin with tall dermal papillae (keratinized stratified squamous epithelium with hair follicles and sebaceous and sweat glands).
Cutaneous region
Name the histological lip region described: a stratified squamous epithelium supported by connective tissue containing blood vessels responsible for the red color of this region; no salivary glands
Vermillion/red region
Name the histological lip region described: stratified squamous epithelium, supported by a dense lamina propria and a submucosa, closely bound by connective tissue fibers to the underlying skeletal muscles.
Oral mucosa region
Name and describe the papillae of the tongue.
Filiform (most numerous) - covered by keratinized stratified squamous epithelium
Fungiform - same covering as filiform, mushroom-shaped, taste buds
Circumvallate - ducts of glands of von Ebner, side taste buds
Where are taste buds found in relation to the papillae of the tongue?
Within the circular cleft
Gustatory cells contact masticated food through:
Taste pores
What are the three types of cell in the tongue related to taste?
Gustatory
Supportive
Stem (basal)
What three precusor cells give rise to the teeth?
Ameloblast (enamel)
Odontoblast (dentin)
Cementoblast (cementum)
Name the respective product of each of the following cells:
Cementoblast
Ameloblast
Odontoblast
Cementum
Enamel
Dentin
What is the hard, outer layer of the tooth?
What lies just deep to this layer?
Enamel;
dentin
The _________ ligament secures the tooth to alveolar bone via the ligament’s interface with the tooth through ___________.
Periodontal;
cementum
Name the layers of the esophagus from the inner mucosa to the outermost layer (assume above the diaphragm).
Mucosa
- Epithelium*
- Lamina propria*
- Muscularis mucosa*
Submucosa
- Glands, blood vessels*
- Meissner’s plexus*
Muscularis externa
- Inner circular layer*
- Auerbach’s plexus*
- Outer longitudinal layer*
Adventitia
Serosa (below diaphragm)
What esophageal covering is only present below the diaphragm?
Serosa
True/False.
Contraction of the muscularis mucosae produces ___________ folds in the esophagus.
Longitudinal
What type of epithelium lines the esophageal lumen in a healthy esophagus?
Non-keratinized stratified squamous epithelium
The muscularis of the upper 1/3 of the esophagus is made of _________ muscle.
The muscularis of the upper 2/3 of the esophagus is made of _________ muscle.
The muscularis of the upper 3/3 of the esophagus is made of _________ muscle.
Striated;
striated + smooth;
smooth
Describe the glands of the esophagus.
Tubuloacinar glands arranged in small lobules that drain into a single duct
What type of gland is found in the esophageal mucosa?
What type of gland is found in the esophageal submucosa?
Cardiac mucus glands (lamina propria);
esophageal glands
From proximal to distal, what are the four general regions of the stomach?
Cardia,
fundus,
body,
pyloric antrum
The stomach lumen is lined by longitudinal folds called:
Rugae
Describe the three regions of the general anatomy of a gastric gland.
The pit (surface mucous cells),
the neck (pinch point),
the body (parietal, chief, neuroendocrine, and stem cells)
Describe the histology of a gastric gland.
Describe the histology and function of a gastric parietal cell.
Histology: microvillous, numerous cannaliculi and mitochondria
Function: secrete HCl and intrinsic factor
Describe the histology and function of a gastric chief cell.
Histology: apical zymogen granules, basal RER, supranuclear Gogli
Function: secrete pepsinogen
What are the four general layers found throughout the GI tract?
Mucosa,
submucosa,
muscularis externa,
serosa
From anatomically largest to smallest, name four mechanisms by which the small intestine increases its surface area.
Plicae circularis
Villi
Crypts of Lieberkuhn
Microvilli
Define: crypts of Lieberkuhn.
Invaginations of intestinal mucosa extending deep between villi
(at times, all the way down to the muscularis mucosae)
Describe the gastric epithelium.
Simple columnar
What is the difference between gastric mucous cells found on the luminal epithelium and those found in the neck of gastric glands?
Surface - insoluble mucus production
Glandular neck - soluble mucus production
What are some of the products secreted by enteroendocrine cells found in the body of gastric glands?
Cholecsytokinin,
secretin,
gastrin
True/False.
Both the gastric epithelium and the small intestinal epithelium are simple columnar.
True.
What are the five main cells of the small intestine?
Enterocytes
Goblet cells
Enteroendocrine cells
Paneth cells
Stem cells
What main function(s) do Paneth cells of the small intestine serve?
Release lysozymes, defensins, phospholipase A2;
regulate gut flora
What structure innervates/causes villous movement in the small intestine?
Central lacteals are located in what tissue layer?
The submucosal (Meissner’s) plexus;
the lamina propria
True/False.
Most small intestine lymphatics are in the lamina propria, and the central lacteals are located in the submucosa.
False.
Most small intestine lymphatics are in the submucosa, and the central lacteals are located in the lamina propria.
What function(s) is(are) regulated by the submucosal (Meissner’s) nerve plexus?
Mucosal / submucosal glands;
the muscularis mucosa
What function(s) is(are) regulated by the myenteric (Auerbach’s) nerve plexus?
Peristalsis
Describe the differences in villi shapes between the duodenum, jejunum, and ileum.
D: Leaf-like at apex
J: finger-like
I: shortest
Describe the differences in distinctive structures between the supportive networks of the duodenum, jejunum, and ileum.
D: Brunner’s glands (submucosa)
J: none
I: Peyer’s patches (lamina propria and submocusa)
What type of gland is found only in the duodenum?
Brunner’s glands
What type structure is found only in the ileum?
Peyer’s patches
(also, M cells)
What are M cells of the small intestine?
APCs of the ileal epithelium
Describe the relationship between M cells and Peyer’s patches.
What type of epithelium is found in the large intestine?
Simple columnar
What are the four cell types of the large intestine?
Enterocytes
Goblet cells
Enteroendocrine cells
Stem cells
What visible external structures are formed on the large intestine by the longitudinal layer of the muscularis externa?
The teniae coli
Identify which of the following are present in the large intestine:
Plicae circularis
Villi
Microvilli
Crypts of Lieberkuhn
Goblet cells
Plicae circularis
Villi
Crypts of Lieberkuhn
Microvilli
Goblet cells (in large number)
Besides the colon (ascending, transverse, descending, and sigmoid), what are the other portions of the large intestine?
The appendix,
the rectum,
the anal canal
At the base of what distal structure of the large intestine do the teniae coli converge and end?
The appendix
(note: they end at the base and do not extend onto the appendix)
Describe the lymphoid portion of the appendix.
Large aggregations in the lamina propria and submucosa
Describe the epithelium of the anal canal.
A transition from simple columnar to stratified squamous (with hair follicles and sebaceous glands)
Describe the general histological changes from the esophagus to the colon.
What form of vitamin D comes from the skin upon sun exposure?
D3
How does parathyroid hormone have an effect on vitamin D protein production?
Upregulation of 1-α-hydroxylase in the PCT
After calcium absorption is increased by vitamin D, what protein modulates calcium channels and pumps to prevent cytosolic buildup of calcium within the enterocytes?
Calbindin
What are our main sources of 25-hydroxy vitamin D?
Sun exposure;
diet
Vitamin D acts on what organ systems?
Bones;
the gut
What protein is secreted in the oral cavity and is necessary for vitamin B12 absorption?
Transcobalamin-1
(haptocorrin)
(R-factor)
What two substances must bind B12 in order for it to be properly carried to the absorption site?
What substance is necessary to cleave one of these substances and allow the B12 complex to be absorbed?
Transcobalamin-1 (oral cavity),
intrinsic factor (gastric body);
pancreatic lipases (cleave TC-1)
Vitamin B12 absorption occurs at:
Peyer’s patches (the terminal ileum)
True/False.
B12 deficiencies virtually only occur when there is either an insufficient diet or gastric damage.
False.
There are several other causes (see image).
What four layers are found throughout the digestive tract?
Mucosa
Submucosa
Muscularis externa
Adventitia/Serosa
What are the three portions of the gut mucosa?
Epithelium, lamina propria, muscularis mucosa
True/False.
Many small salivary glands and APCs can be found in the soft mucosa of the cheeks.
False.
Many small salivary glands and APCs can be found in the soft sub__mucosa of the cheeks.
In what directions do the intrinsic muscle fibers of the tongue project?
Where do they attach?
In various crisscrossing directions;
a central septum
Which type(s) of lingual papillae lack(s) taste buds?
Filiform
What type of lingual papilla is not abundant in adult humans?
Foliate