Histo of Accessory organs of GI tract Flashcards
What are the 3 main digestive glands?
- Main salivary glands
- Exocrine Pancreas
- Liver
What are the functions of the secretory products of the 3 main digestive glands?
Lubricating
Protective
Digestion
Absorption
What divides the salivary glands into lobes/lobules and is a route for neurovasculature?
Septa - CT
Secretory cells are grouped into _____ in salivary glands
Acini
What type of cells aid salivary gland acini in secretions?
Myoepithelial cells
Describe how the secretory products are released from a salivary gland
- Acini
- Intercalated Duct
- Striated Duct
- Excretory Duct
Salivary glands release their products via ducts, true or false?
TRUE
What type of epithelium is found in the intercalated ducts of salivary glands?
Cuboidal
What type of epithelium is found in the striated ducts of salivary glands?
Cuboidal to Columnar
What type of epithelium is found in the excretory ducts of salivary glands?
Pseudostratified columnar or stratified cuboidal
What are the 3 main salivary glands?
Parotid
Sublingual
Submandibular
Products and attributes of a parotid gland
- Acini cells release a serous product
- DARK, intensely staining granules within cells
- may have adipocytes (white)
Products and attributes of a sublingual gland
- Acini cells release mostly a mucous product (has both serous and mucous though)
- PALE, faintly staining cells
- lacks defined capsule
Products and attributes of a submandibular gland
- Acini cells release mostly a serous product (has both serous and mucous though)
- SEROUS DEMILUNES
What are serous demilunes and where will you find them?
Cluster of mucous secreting cells with a “hat” of serous secreting cells – looks like a white person wearing a bonnet!!
– Found in submandibular glands
How do serous cells look on a histo image?
DARK, intensely staining
How do mucous cells look on a histo image?
PALE, faintly staining
In a serous demilune, describe its appearance on a histo image
Mucous base = pale
Serous hat = dark staining
– pale inner part with a cap of dark stain
The pancreas has ______ function
Endocrine AND Exocrine
The exocrine pancreas does what?
Secretes digestive enzymes
The endocrine pancreas does what?
Secretes hormones for metabolism
The functional unit of the exocrine pancreas is what?
SEROUS acini = dark staining
The pancreatic acinar cells contain what type of granules and what do they possess?
Zymogen granules
- They possess many proenzymes to digest proteins/carbs/etc.
What is unique about the intercalated ducts in the exocrine pancreas?
They begin within the acinus using centroacinar cells
Describe the main characteristics of the exocrine pancreas on a histo image
Darkly staining pancreatic acinar cells (serous)
- Lightly staining centroacinar cells within the acinus that begin the intercalated ducts
The zymogen granules of the pancreatic acinar cells can do what based on diet?
Increase synthesis of either proteases or amylases based on intake of either more protein or more carbs
How can you distinguish the endocrine pancreas?
LIGHTLY staining islets
List the cell types and what they produce in the endocrine pancreas
alpha = glucagon beta = insulin delta = somatostatin PP = pancreatic polypeptide
How are hepatocytes arranged in the liver?
Arranged into cords
Function of hepatocytes?
Produce bile, metabolism, storage
3 ways to look at a liver structure?
Hepatic lobule
Portal lobule
Liver acinus
Where do hepatocytes secrete bile?
Bile canaliculus
Where are bile canaliculi?
Between adjacent hepatocytes
How do hepatocytes look on a histo image?
Large, polygonal with microvilli, large nuclei and cytoplasm stains eosinophilic
Function of bile?
Fat absorption
Describe the organization of a hepatic lobule
Hepatocytes form irregular plates radiating from a central vein
- Sinusoids run in between plates of hepatocytes
- Peripheral angles of each lobule contain a portal triad
What will you find in the portal triad?
Arterial branch of hepatic artery
Venule branch of hepatic portal vin
Bile ductules (1-2)
In the hepatic lobule, where does blood flow?
Toward the central vein
In the hepatic lobule, where does bile flow?
Away from the central vein
Describe the flow of bile
Bile canaliculi Canals of Hering Bile ductules Merge and enlarge R and L hepatic ducts
What type of cells are in the canals of Hering?
Cuboidal = cholangiocytes
Purpose of sinusoids?
Supply hepatocytes with portal and arterial blood
What type of cells can be found in sinusoids and what is their job?
Kupffer cells - macrophages
Where is the perisinusoidal space?
Between hepatocytes and sinusoidal epithelium
Purpose of perisinusoidal space?
Creates space for exchange of materials between the blood and hepatocytes - increases surface area for microvilli too
Where is the periportal space?
Between hepatocytes and the portal triad CT
Purpose of the periportal space?
Collects excess fluid from the perisinusoidal space and drains it to lymphatics
What type of cells may you find in the periportal space?
Ito cells - store fat and vitamin A
What is the portal lobule?
Triangle between 3 adjacent central veins
What does the portal lobule outline?
Drainage pathway for bile
What is the liver/hepatic acinus?
Diamond shape occupying adjacent lobules with a sinusoid running down the middle
What is the purpose of the liver acinus?
Shows zones where the most O2 and nutrients will be received (and toxins)
What can the liver acinus explain?
Distribution of liver damage from ischemia (zone 3, far away from sinusoid) or from toxins (zone 1, adjacent to blood supply)
Purpose of gallbladder?
Store bile
What type of epithelial cells are located in the gallbladder?
Simple columnar
The gallbladder has NO _______ and ______
Muscularis mucosae and submucosa
The muscularis externa for the gallbladder is oriented how?
In ALL directions
Rokitansky - Aschoff sinuses
Deep pockets of mucosa that extend to the muscularis externa in the gallbladder
Rokitansky - Aschoff sinuses increase your risk for?
Gallstones
Where can you find Rokitansky - Aschoff sinuses?
Gallbladder
