Histology: Digestive Tract Flashcards
Label the 4 types of papillae.
What cells line the oral cavity, oropharynx and laryngopharynx?
- stratified squamous epithelium
- generally not keratinised
What cells line the nasal cavity and nasopharynx?
-ciliated columnar epithelial cells -> respiratory epithelium
What cells line the anterior 2/3 of the tongue?
-Stratified squamous epithelium
What are the cells that line the posterior 1/3 of the tongue and what lie in its submucosa?
- smooth stratified squamous eptihelium
- lymphoid aggregates
What are the four type of papillae that line the tongue and where does each lie?
- fungiform -> on the front and middle
- circumvallate -> at the back of the tongue
- foliate -> sides of the tongue
- filiform -> all over the anterior 2/3 of the tongue
Which papillae do not contain tastebuds?
Filiform
What are the 4 components of the lymphoid tissue of the pharynx?
- palatine tonsils
- lingual tonsils
- tubal tonsils
- pharyngeal tonsils
What tissue is this a histological section of and what are the labels?
-palatine tonsil
What are the 4 major layers of the digestive tract?
- mucosa
- submucos
- muscularis externa
- serosa/adventitia
What does the mucosa comprise of?
- epithelium
- lamina propria
- muscularis mucosae
What does the epithelium in the mucosa sit on?
The basal lamina -> extracellular matrix secreted by the epithelial cells
What 2 components does lamina propria comprise of?
- loose connective tissue
- GALT -> gut associated lymphoid tissue
What does the muscularis mucosae comprise of?
thin layer of smooth muscle
What does the submucosa comprise of?
- loose connective tissue
- submucous plexus (part of the ENS)
What does the Muscularis Externa comprise of?
- two thick layers of smooth muscle: inner circular layer and outer longitudanal muscle
- myenteric plexus (part of ENS)
What are the serosa/adventitia made of and what is their purpose?
- layer of connective tissue
- suspends organs in the GI tract or attaches them to other organs
What is the difference between serosa and adventitia?
- serosa: made of two membranes, made of epithelial cells, visceral and peritoneal, contains serosal fluid between these membranes, covers organs that are intra-peritoneal e.g. stomach, small intestines
- adventitia: made of loose connective tissue, binds organs to the body wall, covers organs that are retro-peritoneal e.g. pancreas, colon
What is this a cross section of and fill in the labels.
Oesophagus
What tissues make up the upper third, middle third and bottom third of the oesophagus?
- upper 1/3: skeletal muscle
- middle 1/3: transition to smooth muscle
- bottom 1/3: smooth muscle
What are the only two parts of the GI tract with mucous glands in the submucosa?
- oesophagus
- duodenum
What is this a cross section of and fill in the labels.
submucosal glands of the oesophagus
Describe the cells at the gastro-oesophageal junction.
They change abruptly from the stratified squamous epithelium of the oesophagus to the simple columnar epithelium of the cardia of the stomach
What is this a diagram of and fill in the labels.
Where do gastric glands of the stomach lie?
In the bottom of the gastric pits
Label the parts of this gastric pit.
What is this a section of?
gastric pit
What 2 cells is the isthmus mostly made up of?
- stem cells
- parietal cells
What cells is the neck of the gastric pit mostly made up of?
- Surface mucous cells
- parietal cells
What 3 cells is the fundus of the gastric pit mostly made up of?
- chief cells
- parietal cells
- enteroendocrine cells
What cells line the whole gastric pit?
Surface mucous cells
What do chief cells produce?
Digestive enzymes e.g. pepsinogen, gastric lipase
What do parietal cells produce?
hydrochloric acid
What does the isthmus mark the point of in the gastric pit?
Where the gastric pit becomes the gastric gland
Why does the muscularis externa of the stomach have an extra layer and where does it lie?
- to aid churning
- lies internal to the circular layer and oblique to it
What cells
Label the parts of the stomach
Describe the difference in the gastric pits of the cardia, body and pylorus of the stomach.
- cardia: deep gastric pits with loose, tortuous glands
- body: shallow gastric pits with long straight glands
- pylorus: deep gastric pits with branched, coiled densely packed glands
What is the mucosa of the small intestine made up of?
- villi
- crypts of Lieberkuhn
What layer of the stomach wall thickens to form the pyloric sphincter?
Inner circular layer of the muscularis externa
What marks the gastroduodenal junction?
Pyloric sphincter
What are the differences between the duodenum, jejenum and ileum?
- duodenum: contains Brunner’s glands
- jejenum: tall villi located on plicae circularis
- ileum: shorter villi with Peyer’s Patches
What is the plicae circularis of the jejenum?
circular folds of the mucosa and submucosa
What are Peyer’s Patches?
- Part of GALT -> lymphatic tissue
- lie in mucosa and extend into submucosa of ileum
List the 5 cells of the small intestinal epithelium.
- enterocytes
- goblet cells
- paneth cells
- stem cells
- enteroendocrine cells
What are enterocytes and what is significant about them in the small intestine?
- absorptive cells
- covered in microvilli in the small intestine
What do goblet cells produce?
mucin
What do Paneth cells produce and where are they found?
- antibacterial products to control gut flora
- at base of Crypts of Lieberkuhn
What is this a section of?
Peyer’s Patches in the ileum
Fill in the labels.
What do Brunner’s glands secrete and what stimulates them to secrete?
- alkaline mucous to protect from acidic chyme
- the acidic chyme from the stomach
What is this a section of and fill in labels.
Duodenum
What is this an image of?
Plicae circularis
Describe the mucosa of the large intestine in terms of arrangement and what cells it contains.
- arranged into crypts, like test tubes in a rack
- no villi
- enterocytes (for removing salts and water)
- goblet cells
What is the taeniae coli of the colon?
- longitudanal muscle of the colon is arranged into 3 strips along the ascending, transcending and descending parts of the colon into taeniae coli
- they create the haustra.
How does the appendix differ to the colon tissue.
- contains a lot of lymphoid tissue
- less crypts
What happens to the cells in the rectoanal junction?
Rectal mucosa transitions abruptly to non-keratinised stratified squamous epithelium of anal canal which then becomes keratinised stratified squamous epithelium
Where do the two plexuses of the enteric nervous system lie?
- inbetween the layers of the muscularis externa: myenteric plexus
- in the submucosa: submucosal plexus
What does the myenteric plexus control and what does the submucosal plexus control?
- myenteric: controls gut motility through circular and longitudanal layers
- submucosal: controls the muscle in the muscularis mucosae and regulates epithelial secretions
How are the neurons of the enteric nervous system arranged?
In groups called ganglia
What is a ganglion?
a group of neurons living outside of brain and spinal cord
What cells are associated with protective function in the gi tract mucosa?
non-keratinised stratified squamous epithelium
What cells are associated with absorptive function in the gi tract mucosa?
- simple columnar epithelium
- villi
- tubular glands
What cells are associated with secretory function in the gi tract mucosa?
simple columnar epithelium with tubular glands
What cells are associated with protective and secretory function in the gi tract mucosa?
