GI Flashcards
What type of epithelium covers the oral cavity, oropharynx and laryngopharynx?
Stratified squamous epithelium (generally not keritanized)
What kind of epithelium covers the nasal vaity and nasopharynx?
Respiratory epithelium (see respiratory histology flash cards)
How is the epithelium on the anterior 2/3 of the tongue different from the epithelium on the posterior 1/3?
Anterior- thin in ventral surface, thick with papillae on dorsal
Posterior- smooth epithelium which, except from the circumvallate papillae, lacks papillae. Has lymphoid aggregates in the submucosa. There are crypts.
Name the four papillae of the tongue?
Fungiform
Circumvallate
Foliate
Filiform
What are the four major layers of the GI tract?
Mucosa
Submucosa
Muscularis Externa
Serosa
What is contained within the mucosa?
Epithelium
Lamina Propria
Luscularis Mucosae
What are the two layers in the muscularis externa?
The inner circular and the outer longitudinal muscles
What happens at the gastro-oesophageal junction?
Transition from stratified squamous epithelium of the oesophagus to the columnar epithelium of the cardia of the stomach
What is histologically important about the stomach mucosa?
Gastric pits- contain gastric glands at the bottom which secrete enzymes and acid
‘pink fried egg with a purple nucleus’
What is at the isthmus of the gastric glands?
Parietal cells
What is the neck of the gastric glands made up of?
Mucous and stem cells
What is the base of the gastric glands made up of?
Few parietal calls, chief cells and neuroendocrine cells.
What is the mucosa in the cardia of the stomach>
Deep gastric pits
torturous gland
What is the body of the stomach?
Shallow gastric puts
long straight glands
What is the mucosa of the pyrlorus like?
Deep gastric pits with branched, coiled gastric glands
What is interesting about the muscularis externa of the stomach?
it contains an additional layer. This layer is oblique to the usual circular and longitudinal muscle layers and is located internal to the circular layer. This layer aids the churning action of the stomach.
What happens at the gastroduodenal junction?
Transition from stomach mucosa to duodenal mucosa.
The inner circular layers of muscle thickens= pyloric sphincter
What are the crypts in the small intestine called?
Crypts of Lieberkuhn
What is contained in the submucosa of the duodenum?
Brunner’s glands- alkali producing glands
Where is the tallest villi in the small interstine located?
Jejunum
What are the permenant circular folds of the jejunum called?
The plicae circularis
Folds of the mucosa AND submucosa
What charecterises the ileum?
Peyer’s patches in submucosa and lamina propria
What are enterocytes?
Simple Tall comumnar epithelium with a brush border
Absoptive
What are paneth cells?
At base of crypts- defensive
What are goblet cells?
Produce mucin to protect epithelium and lubricate passage of material.
What are neuroendocrine cells?
: Produce hormones that contribute to the control of secretion and motility.
What are stem cells?
Found at the base of the crypts of Lieberkuhn, they divide to replenish epithelium.
What are the two cell types in the large intestine?
Absorptive cells- removes salts and water
Goblet cell
What is the name for the three strips of the longitudinal muscle in the large intestine?
teniae coli
What happens at the rectoanal junction?
Transition from columar epithelium in the rectum to stratified squamous epithelium in the anal canal
Where is the ganglia of the enteric nervous system located ?
In between the two muscle layers that make up the muscularis externa
What is the nerve plexus at the muscularis externa of the gut called?
Myenteric plexus
What is the network of neurons in the submucosa called?
The submucosal plexus
