Gi histology Flashcards
The oral cavity, oropharynx and laryngopharynx is made up of?
Stratified squamous epithelium that is usually non keratinized
The nasal cavity and nasopharynx is made up of
Respiratory epithelium normally
The tongue consists of 4 types of papillae
Circumvallate
Follate
Fungiform
Filiform
The anterior 2/3rds of the tongue consist of
Stratified squamous epithelium
thin on ventral surface
thick on dorsal surface - papillae
The posterior 1/3rd of the tongue consists
Smooth stratified squamous epithelium
few tastebuds
extensive lymphoid aggregate
The pharynx
Ring of lymphoid tissue
4 tonsils = palatine, lingual, tubal and pharyngeal
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Layers of GI tract
Mucosa
Submucosa
Muscularis Externa
Adventitia/ Serosa
The mucosa is made up of
Epithelium
Lamina propria
Muscularis mucosa
The submucosa
loose connective tissue
muscularis externa
inner layer of circular muscle
outer layer of longitudinal muscle
serosa/ adventitia
loose connective tissue
what transition occurs at the gastro-oesophageal junction
stratified squamous epithelium –> simple columnar epithelium
What are present in the mucous epithelial layer
gastric pits and at the bottom gastric glands
What are the three divisions of the gastric pit
isthmus
neck
fundus
The isthmus is predominantly made up of
parietal cells
The neck is predominantly made up of
mucous cells
The fundus is predominantly made u of
chief cells
role of parietal cells
secrete hydrochloric acid
role of chief cells
produce digestive enzymes
describe the differences in gastric pits in various parts of the stomach
cardia - short gastric pits
fundus - narrow gastric pits
pylorus - deep gastric pits
describe the differences in glands in various parts of the stomach
cardia - closely packed torturous
pylorus - long straight glands of low density
fundus - greatest density
what is special about the muscular layers of the stomach
contains an additional muscular layer which lies internally to the circular layer
Gastrodoudenal junction
thickened layer of inner circular muscle
3 parts of small intestine
Duodenum - 25cm
Jejunum - 2m
Ileum - 2.5m
What is special about the duodenum
Contains Burners glands
What does the jejunum mainly consist of
Enterocyes
What is special about the ileum
Peyer’s Patches
What are Burner’s Glands
glands in submucosa
produce an alkaline solution in response to chyme
What are Enterocytes
Columnar cells with a brush border
Responsible for absorption
Peyer’s patches
Aggregates of lymphoid tissue
What cells does the small intestine contains
Enterocytes
Goblet cells
Paneth cells
Enteroendocrine cells
What do enteroendocrine cells do
Produce horomones - gastrin, CCK, VIP
Role of paneth cells
Defensive function at base of Liberkuhn
secrete lysosomes + defensins
The 2 main cells of the large intestine
Absorptive cells
Goblet cells
What is notable about the large intestine histology
Long simple tubular glands which extend to the muscularis mucosae
Describe the longitudinal muscle if the large intestine
3 muscular bands - teniae coli
Describe the histology of the appendix
Continuation of the caecum
Has crypts and circular lymphoid tissue
lymphoid tissue decreases with age
Rectoanal junction
non keratinized stratified squamous epithelium in the anal canal with keratinized stratified squamous epithelium surrounding the skin
What is the nervous system called specific to the GI tract
enteric nervous system
How is the enteric nervous system stimulated
Partly by autonomic nervous system
Also has ability to stimulate itself
Name the plexuses involved in the enteric nervous system
Submucosa
Myenteric plexus
What is the role of the submucosa plexus
Contributes to absorption
Regulates movement of muscularis mucosae
Define a ganglion
Nerve cell body which exists outside the brain or spinal cord
non-keratinized stratified squamous epithelium
oral cavity
pharynx
oesophagus
anal canal
simple columnar epithelium with extensive tubular glands
stomach
simple columnar epithelium with villi & tubular glands
small intestine
simple columnar epithelium with tubular glands
large intestine
what makes up the parenchyma and pancreas
glandular epithelium
what is the liver covered by
collagenous connective tissue covered by a layer of mesothelial cells
What is the liver divided into
segments/ lobules
what does the portal triad consist of
portal vein
hepatic artery
bile duct
What are bile ducts lined by
cholangiocytes
Where is the central vein
In the centre of the liver lobule
Describe the layout from the red blood cell outwards
Red blood cells which is fenestrated
layer of epithelium
space of Disse
hepatocytes
Explain stellate cells
Found in space of Disse
Produce collagen
Store vit A
Explain Kuppfer cells
Resident macrophages in the sinusoids
When do stellate cells have the greatest role to play
Scarring = fibrosis
What organ is responsible for producing bile
Liver
Liver is formed by
Hepatocytes
What are the functional cells of the liver
Cholangiocytes
What type of cells modify bile
Cholangiocytes
What is responsible for the pigmentation of bile
Bilirubin
Where is bilirubin produced
Spleen from the breakdown of haem
Explain how bile travels
Travels via bile caniculi to bile ducts to portal tracts
What are bile caniculi
Tight junctions formed by adjacent hepatocytes
What is bile
Alkaline solution formed by H2O, phospholipids, bilirubin and bile salts
layers of gallbladder
simple columnar epithelium
lamina propria - loose CT, blood vessels and lymphatics
layer of smooth muscle
adventitia
explain the relationship between bile and the gallbladder
Bile from the liver travels via hepatic duct and causes a back up in the common bile duct which leads to bile flowing up via the cystic duct and entering the gallbladder
Na and Cl flow through epithelial cells and water follows
Bile then drains via the lymphatics which are present in the lamina propria
Inflammation of the gallbladder is known as
Cholecystitis
What stimulates the gallbladder
Nervous control - vagal
Release of hormone cholecystokinin via enteroendocrine cells
What lines the gallbladder
Tall columnar epithelial cells with a brush border
What makes the pancreas unique
It is both an endocrine and exocrine organ
Outline the exocrine function
Produce a litre of digestive juices
name the digestive juices of the exocrine function of the pancreas
proteases - breakdown proteins
lipases - breakdown lipids
nucleases - breakdown DNA/ RNA
What cell is responsible for the exocrine function of the pancreas
acinar cells
Where do the digestive juices go
Via pancreatic duct to the 2nd part of the duodenum
What is the role of enteropeptidases
converts inactive proenzymes (zymogens) into their active form
Why are exocrine cells basophilic and stain easily
high amounts of RER
the endocrine pancreas is made up of
Islets of Langerhans
What is the role of the islets of langherhans
produce hormones
what makes up the islet of langerhans
alpha cells
beta cells
delta cells
alpha cells are responsible for
secreting glucagon
beta cells are responsible for
secreting insulin
gamma cells are responsible for
secreting somatostatin
