Accessory glands Flashcards
What are glands?
Organised clusters of secretory units
What do glands arise from?
Invaginated epithelial cells
Describe the increasing complexity of a digestive gland (ducts deeper into the gland)
Main duct
Lobar duct
Interlobar duct
Intralobular duct
Striated duct
Intercalated duct
Acinus
What cells line the lobar duct?
Stratified columnar epithelia
What cells line the interlobar duct?
Pseudostratified columnar epithelium
What cells line the intralobar duct?
Cuboidal to columnar epithelia
What cells line the striated duct?
Cuboidal to columnar epithelia
What cells line the intercalated duct?
Low cuboidal epithelium
What is an acinus?
Rounded secretory units
What does saliva contain?
Proteins, glycoproteins (mucus), ions, water and IgA.
What are the two portions of the salivary gland?
Secretory portion
Duct portion
What cell types make up the secretory portion of the salivary gland?
Serous cells
Mucous cells
Myoepithelial (basket) cells
What is a characteristic feature of the myoepithelial basket cells?
Have several long processes that envelope the acinus
What is characteristic about the duct portion of the salivary glands?
Highly branched levels
What are the 3 major salivary glands?
Parotid
Submandibular
Sublingual glands
What is mainly secreted from the parotid?
Serous secretion with high levels of the enzyme amylase
What salivary gland produces most of the saliva?
Submandibular
What do minor salivary glands mainly secrete?
Mucous
Talk about how enzymes are stored in pancreas and salivary cells?
Stored as zymogens in acinar cells - released by exocytosis
Describe what system innervates salivary glands
Post ganglionic fibres of autonomic nervous system
How are salivary and pancreatic ducts similar
Both have branching ductal system which epithelial cells secrete into
Both compromise secretory units (lobules) made of an acinus - intercalated duct - intralobular duct - interlobular duct - pancreatic/salivary duct
Both store zymogen granules in acinar cells
Desribe difference histologically between endocrine and exocrine pancreas
Exocrine pancreatic acinus release enzymes into duct
Endocrine pancreas cells release hormones into capillaries (capillaries in middle of islets)
What do centroacinar cells do?
Pancreas - Form intercalated ducts and secrete buffer solution
What is the largest gland?
The liver
How many lobes is the liver divided into?
4
What epithelia/connective tissue surrounds the liver?
Glisson’s capsule - squamous epithelium connective tissue
What are epithelial cells of the liver?
Hepatocytes
Where do blood vessels enter and leave the liver?
Porta hepatis
Where do vessels leave to the gall bladder from liver?
Hepatic ducts
What are the three models of liver organisation?
Classical liver lobule
Portal lobule model
Acinar model
What is the the classical liver lobule?
Central vein, seen as single holes
Hepatocytes radiating from the central vein separated by vascular sinusoids.
Drains blood from portal vein and hepatic artery to hepatic/central vein
What is the portal liver lobule?
The portal triads drain into a central site/canal
Important in draining bile from hepatocyte to bile duct
What is the portal acinus lobule?
Based on functional considerations
Gradients of oxygen/metabolic processes
Diamond arrangement of oxygenated blood supply from portal canals and drain into central vein of lobule
Where 3 classical lobules are in contact with each other form portal areas it is called …
Triad
Portal areas house …
Branches of hepatic artery, Tributaries of portal vein, Interlobular bile ducts
Spaces between hepatocytes occupied by
Sinusoids
What are sinusoids?
Small blood vessels with discontinuous endothelium
Spaces between hepatocytes membrane and sinusoidal lining …
Space of Disse
How do veins and sinusoids appear on section?
Veins: large non-stained oval
Sinusoids: smaller non stained region (longer shape but thinner)
How do hepatocytes normally appear?
Branched, usually one cell thick and at least one surfaces faces a blood sinusoid.
What lies on the basolateral domain of the hepatocyte, what does it absorb and secrete?
Sinusoidal: adsorbs blood-borne substances and secretes plasma proteins (blood clotting)
What lies on the apical domain of the hepatocyte?
Canalicular: borders the bile canaliculus, sealed at sides by occluding junctions to prevent leakage of bile
What are Kupffer cells?
Resident macrophages of liver, line sinusoids
What is the role of Kupffer cells?
Involved in breakdown of red blood cells
Involved in liver’s response to: infection, toxins, ischemia resection and other stresses
What are hepatic stellate cells also known as?
Perisinusoidal cell, Ito cell, Hepatic pericyte, lipocyte, parasinusoidal cell, fat-storing cell
What is the role of hepatic stellate cells?
Liver damage - stellate cells activated
Transition from quiescent vitamin A-rich cells into, proliferative, fibrogenic, contractile myofibroblasts
What junctions flank bile ducts?
Tight junctions
What is the role of the gall bladder?
Acts as a reservoir for the bile produced by the liver
Concentrates the bile and adds a quantity of mucus to it
Discharges its contents in response to the entry of fatty foods into the duodenum
What mucosa does the wall of the gall bladder consist of?
Folded mucosa
What are the 4 cell types/layers of the gall bladders folded mucosa?
Epithelium
Lamina propria
Smooth muscle
Adventitia
What is the epithelia of the gall bladder?
Simple columnar apical brush border of microvilli
Does the gall bladder have a muscularis mucosae?
No
How are muscle fibres arranged in the gall bladder?
Not arranged in distinct layers
What defines a centroacinar cell?
Duct cells that penetrate into the central region of the acini
What is the role of the spleen?
Phagocytosis and immune responses in adult.
In foetus it is an important site of haematopoesis
What does the spleen consist of?
Thin fibrous capsule
White pulp - lymphoid tissue (B and T lymphocytes develop)
Red pulp - macrophages
Fibrous trabecular – support
How can white pulp and red pulp be distinguished on H&E?
White pulp - more purple darker patches (circular)
Red pulp - pinker, rest of spleen
A hepatic vein tributary is a component of each portal triad…
False
Where is bile that enters the bile canaliculi carried to ?
The portal triads
