Histology Flashcards
The oral cavity, oropharynx and laryngopharynx is covered by …..
stratified squamous epithelium which is generally not keratinised
The anterior 2/3 of the tongue has …..
stratified squamous epithelium which is thin on the ventral surface (top) and thick with papillae on the dorsal surface
The posterior 1/3 of the tongue is covered by…
smooth, stratified squamous epithelium
What are the four types of papillae on the tongue?
filiform, fungiform, circumvallate and foliate papillae
On entrance to the oropharynx there is a ring of lymphoid tissue composed of …
palatine tonsils, lingual tonsils, tubal tonsils and pharyngeal tonsils
Explain the four major layers of the GI tract
1) Mucosa (epithelium, lamina propria, muscularis mucosa)
2) Submucosa of loose connective tissue
3) Muscularis externa which is two thick layers of muscle- an inner circular and an outer longitudinal
4) Serosa or adventitia which is an outer layer of connective tissue
The oesophagus contains _____
Its distinctive characteristic is _______
non-keratinised stratified squamous epithelium
distinctive characteristic is mucous glands contained within the submucosa
Type of epithelium in the stomach is
simple columnar epithelium with spaces between for gastric pits and glands
In the stomach parietal cells are
specialised cells that secrete hydrochloric acid
In the stomach chief cells are
cells that produce digestive enzymes
In the cardia and pylorus of the stomach the gastric pits are ______ than in the body of the stomach
deeper
What is special about the muscular externa of the stomach?
it contains an additional layer internal to the circular layer thought to aid the churning action of the stomach
What is the difference in the mucosa of the small intestine
It changes to villi- finger like projections for absorption
The duodenum of the small intestine contains __1___ glands in the __2____ which when stimulated by the presence of ___3__ produce a thin ___4___ mucous to ____5_____
1) Brunner’s
2) submucosa
3) chyme
4) alkaline
5) neutralise the acidic chyme
The jejunum of the small intestine contains the ___1___ villi which are located on the _____2_______ which are ___3_____
1) tallest
2) plicae circularis
3) permanent circular folds on the mucosa
The ileum of the small intestine is characterised by ___1___ villi and aggregations of lymphoid follicles called ______2_______ found in the ____3_____
1) shorter
2) Peyer’s patches
3) submucosa often extending into the lamina propria
In the small intestine the most common epithelial cell is _________ these are ________
enterocytes- simple columnar epithelium with a brush border
The two principle types of large intestinal epithelium are … and their purpose…
absorptive cells for removal of salts and water
goblet cells for secretion of mucus to lubricate the colon
In the large intestine how are the goblet cells arranged?
straight tubular glands referred to as crypts that extend down to the muscular mucosae
Explain the difference in the smooth muscle of the large intestine
it is not continuous but is found in 3 muscular strips called teniae coli
Structure of the appendix?
This is similar to the rest of the colon
Crypts are less abundant and there is typically a circular arrangement of lymphoid tissue in the submucosa and often the lamina proprietary
Structure of the rectum?
Similar in structure to the rest of the large bowel
What happens at the rectoanal junction?
Abrupt transition to become stratified squamous epithelium in the anal canal
What happens at the anal sphincter?
The stratified squamous epithelium undergoes a gradual transition to that of skin.
What is the liver covered by?
A collagenous connective tissue capsule which is covered by a layer of mesothelium
Each liver lobule is approximately ___1_____ and has a branch of hepatic vein (centrolobular vein) at its ___2___
and ____3______ at each corner
1 hexagonal
2 centre
3 portal triads/ tracks
Portal triads contain….
hepatic portal vein, hepatic portal artery and the bile duct
How does the bile duct differ from the blood vessels?
it is lined by simple cuboidal cells called cholangiocytes
The main cells of the liver are? These are?
Hepatocytes- polyhedral epithelial cells
Hepatocytes are arranged in ___1___ with spaces between called ___2____ for ___3_____
1 sheets
2 sinusoids
3 blood to flow through
Sinusoids are lined by ___1____ there is a narrow space between these and the hepatocytes called _____2_____
1 endothelial cells
2 space of Disse
What are portal tracts accompanied by?
collagenous connective tissue
Where are hepatic stellate (ito) cells found?
scattered in the space of Disse
What are hepatic stellate (ito) cells?
modified fibroblasts that make connective tissue as well as storing vitamin A in their fat droplets.
What can happen in some pathological conditions involving hepatic stellate cells?
they transform into myofibroblasts and produce scar tissue in the liver causing cirrhosis
What are resident macrophages of the liver called and where are they found?
Kupffer cells found within the sinusoids
What cell is bile produced by?
hepatocytes
What are bile cannaliculi?
small channels formed by right junctions in the cell membrane of adjacent hepatocytes that allows bile to flow from hepatocytes to the bile duct.
The gall bladder is a muscular sac lined by ___1_____
backed by _________________2_______________
1 simple columnar epithelium
2 lamina proprietary of loose connective tissue rich in blood vessels and lymphatic vessels, a coat of smooth muscle and an outer collagenous layer of adventitia
What is special about the smallest ducts in the pancreas?
They extend into the acinus and are called centroacinar, they don’t stain as intensely as the cells around them
What does the endocrine system of the pancreas consist of?
Small scattered islands of tissue called islets of langerhans which produce a number of hormones including glucagon and insulin
