Histiology Flashcards
what is the histology of oral cavvity, oropharynx and laryngopharynx?
squamous epithelium
not keratinised
what is the histology of the nasal cavity and nasopharynx?
resp epithelium
what is the histology of the anterior 2/3 of the tongue?
stratified squamous epithleium
thin on ventral surface
thick and with papillae on the dorsal surface
what is the histology of the posterior 1/3 of the tongue?
- covered by smooth stratified squamous epithlium
- circumvalllate papillae lacks papillae but does have a substantial lymphoid aggregates in the mucosa
what are the 4 types of tongue papillae?
- fungiform
- circumvallate
foliate
filiform
which tongue papillae has no tastebuds
filiform
what is the oropharynx made up of anatomically?
- ring of lymphoid tissue composed of palatine tonsils, lingual tonsils, tubal tonsils and pharyngeal tonsils (adenoids)
from the oesophagus to the anal cavity, what is the digestive tract histologically composed of?
- mucosa = epithelium, lamina propria and muscularis mucosae
- submucosa
- muscularis externa
- serosa/ adventitia
what does the epithelium sit on?
basal lamina
what is the lamina propria?
loose connective tissue
what is the muscularis mucosae?
thin layer of smooth muscle
what is the submucosa?
loose connective tissue
what is muscularis externa?
two thick layers of smooth muscle ,an inner circular layer and an outer longitudinal layer
what is the serosa/adventitia?
outer layer of connective tissue that either suspends the digestive tract or attaches it to other organs
where can you find a mucosa above a submusoca?
oesophagus
what is the gastro-oesophageal junction?
- junction from stratified squamous epithelium of oesophagus to simple columnar epithelium of the cardia of the stomach
where are gastric pits and gastric glands found?
in stomach epithelium
gastric pits = at top
gastric glands = at bottom
what are gastric pits line by?
surface mucous cells
- secretes mucus which protects the lining of the stomach
what is the isthmus?
the junction ebtween gastric pits and gastric glands
what cells make up the isthmus?
parietal cells and stem cells
what is the neck in the stomach epithelium made up of?
muscous cells nad partieal cells
what is the fundus (base) of the stomach epithelium made of?
chief cells, few paritetal cells and nterendocrinecalles (neuroendocrine cells)
what is a chief cell?
digesting enxyme secreting cell
what is a parietal cell?
hydrocholic acid producing cell
what are the gastric pits like in the cardia of the stomach?
deep gastric pits that branched into loosely packed tortuous glands
what are the gastric pits like in the body of the stomach?
shallow gastric pits with long gastric glands
what are the gastric pits like in the pylorus of the stomach?
deep gastric pits with branches, coiled gastric glands at a higher density than in the cardia
what is the extra layer in the muscularis externa of the stomach?
the layer is oblique to the usual circular and longitudinal muscle layers and is located internal to the circular layer
what is the gastroduodenal junction?
transition from the stomach mucosa to duodenal mucosa
it is an inner, circular layer of smooth muscle is markedly thickened to form the pyloric sphincter
what does the surface of the small intestine contain?
- vili
what is the histology of the duodenum?
- contains burnner’s glands in the submucosa
what is the histology of the jejunum?
tallest vili, located on permanent circular folds of the mucosa and submucosa, the plicae circularis
lymphoid follicles infrequent
what is the histology of the illeum?
charcterised by shorted vili and aggregation of lymphoid follicles called peyers patches found in the submucosa and often extending into the lamina propria
what cells are found in the small intestine?
enterocytes, goblet cells, paneth cells, enteroendocrine cells. stem cells
what are enterocytes?
most numerous cells
tall columnar cells with a brush border
- principle absorptive cell
what are goblet cells?
- produce mucin to protect epithelium and lubricate passage of material
what are paneth cells?
- found at base of crypts
- defensive function
- regulate bacterial flora
what are enteroendocrine cells?
- produce hormones that conribute to secretion and motility
what are brunners glands and where are they found?
- glands located in the submucosa
- found in the duodenum only
- when they are stimulated by chyme, they produce a thin, alkaline mucous to neutralise the chyme
what cells are found in the large intestine?
absorptive cells and goblet cells
what is the histology of the appendix?
- circular arrangement of lymphoid tissue in the submucosa and often the lamina propria
- the lymphoid tissue tends to decline with age
what is the histology of the anal canal?
keratinized straitified squamous epithelium of the surrounding skin
what is the enteric nervous system?
the digetsive tract’s own nervous system
what is the myenteric plexus of the enteric nervous system?
- 2 plexi (one in submucosa and one between the muscle layers of the muscularis externa)
controls gut motility
what is a ganglion?
group of nerve cells living outside the CNS
what is the submucosal plexus of the enteric nervous system?
controls the muscle of the muscularis mucosae and helps regulate secretion in the epithelium
what are the parenchyma (liver) and pancreas composed of?
glandular epithelial cells
what is a portal vein?
it has capillary beds at both ends
what is the histology of the liver capsule?
- liver is covered by a collagenous connective tissue capsule, which in turn is covered by a layer of mesothelial cells (simple squamous epithelium), derived from the peritoneum
what are liver lobules?
- segments of liver
each hexogon has a branch of the hepatic vein (centrolobular vein) (blood out) at its centre and portal triads (blood in) at each corner
what is the portal tract made up of?
- hepatic portal vein
- hepatic artery
- bile duct
- (lymphatic vessel)
what are the main cells of the liver?
hepatocytes which have blood channels called sinusoids
what is the histology of the sinusoids?
- they are lined by endothelial cells (fenestrated)
what is the space of disse?
a narrow space between the endothleial cells of the sinusoids and the hepatocytes
- micro vili project into the space
what is the parenchyma of the liver supported by?
- reticular fibres (type 3 collagen) along with type 1 collagen - this is found in the space of disse
what are hepatic stellate cells and where are they found?
- in the connective tissue of the liver
- found scattered in the space of disse
- they are modified fibroblasts and make connective tissue
- they store votamin A within fat droplets in their cytoplasm
what are kupffer cells?
- macrophages of sinusoids
- these cells remove particulate mater from the blood and help remove worn out RBCs
what is bile?
- an alkaline solution
- bilirubin is contained and it is a pigment which results from the breakdown of hemoglobin in the spleen
how is bile produced?
- by hepatocytes
- bile flows via bile canaliculi towards bile cuts in the portal tracts and thence to the hepatic ducts
what are bile canaliculi?
small channels formed by tight junctions in the cell membrane of adjacent hepatocytes
what is the histology of the gall bladder?
- a muscular sac which
- is lined by simple columar epithelium backed by a alamina propria of loose connective tissue rich is blood vessels and lymphatic vessels, a coat of smooth muslce nad an outer collagenous layer of adventitia
- stores bile
- has a folded mucosa when empty - this flattened when distended
- modified the bile stored within it
what is cholecytitis?
- inflam of the gall bladder
- gallstones have obstructed the cyctsic duct, leading to the expansion of the gall ladder, thickening of hte muscle layers and inflam
why is the pancreas unusual?
it has exocrine and endocrine glands
what does the exocrine glands of the pancreas produce?
- a litre of digetsive juices containgin proteases to break down proteins, lipases to break down lipids, nucleases to break down DNA, amlase to break down startch
- these enter the duodenum via the pancreatic duct
what does the endocrine pancreas consist of?
smalll scattered islands of tissue called islets of langerhans, which produce a nuber of hormones including insulin and glucagon
how is trypsinogen activated in the exocrine panceras?
when ti reaches the duodenum, an enteriopeptidase converts it to the active form - trypsin
what is the acinus like in the pancreas?
centroacinar cells
