Histology of GI Glands Flashcards
Digestive glands have lubricating, protective, digestive, and absorptive functions mediated by their secretory products. What are the 3 main digestive glands?
Major salivary glands: associated with oral cavity through independent excretory ducts
Exocrine pancreas: secretes alkaline aqueous and enzymatic product into the duodenum
Liver: endocrine and exocrine gland with extensive access to blood circulation
______ glands may exist as simple invaginations of the epithelium or may have no contact with epithelial surface. They secrete mucus, hormones, enzymes, and wastes.
Exocrine
_________ = part of exocrine glands that acts as passageway for glandular secretions to be released
________ = cellular part of exocrine glands that synthesize and release secretory product
Excretory duct
Secretory units
Secretory cells of exocrine glands are organized in an _______
Acinus
______ acini = cloudier looking cytoplasm, produce thick, glycoprotein rich product
______ acini = clear-staining cytoplasm, produce a water-based product
_______ = contain a core of mucous cells surrounded by serous demilune
Mucous
Serous
Mucoserous
The secretory component of exocrine glands may be _____ or ________, both of which may be coiled or branched
The duct system may be a _____ gland or _____gland
Tubular; alveolar
Simple (unbranched); compound (branched)
3 possible mechanisms of secretion from exocrine glands. What is the most common for the GI system?
Merocrine = exocytosis of apical end of secretory cells (sweat glands)
Holocrine = disintigration of the secretory cell (sebaceous glands)
Apocrine = release of membrane-enclosed vesicles (sweat glands)
most GI glands are merocrine
Describe general histology of a salivary gland
Secretory (epithelial) cells line the ducts and produce saliva (release controlled by ANS)
CT capsule with septa divides gland into lobes (interlobar septa), and smaller lobules (interlobular), providing rout for neurovasculature
What are the 3 types of salivary glands? Which one is largest?
Parotid (largest)
Sublingual
Submandibular
Which salivary gland is often confused histologically with the pancreas? How can the 2 be differentiated?
Parotid
Differentiated based on presence of adipocytes in parotid gland tissue, as well as presence of islets of langerhans in pancreas
The parotid gland is formed by acini containing exclusively ______ cells with a basal nucleus and an apical cytoplasm with secretory granules.
Granules are rich in proteins, including _____-rich proteins, enzymes, and proteins with ______ activity like cystatins and hystatins.
The parotid gland has the longest _____ ducts. ______ cells can be visualized at the periphery of each acinus
Serous
Proline; antimicrobial
Intercalated; myoepithelial
Which of the salivary glands is considered mixed, but it is predominantly mucous?
Sublingual gland
Describe histological characteristics of the sublingual gland
Lacks defined capsule but is divided by CT into small lobes
Intercalated and striated ducts are poorly developed
Which of the salivary glands has both serous and mucous cells but serous cells predominate?
Submandibular gland
Describe histological features of submandibular gland
Mucous cell-containing acini are capped by serous demilunes (surrounding myoepithelial cells control serous secretions)
Intercalated ducts are shorter and striated ducts are longer than those in parotid gland
Hepatic _____ = polygonal structures that comprise functional unit of the liver
_______ = liver cells that function in metabolism, storage, and bile production (similar to acinar cells in that they secrete an exocrine product but they are organized in columns)
Lobules
Hepatocytes
Components of hepatic lobules
Central venule in core of hepatic lobule - collects blood in hepatic sinusoids
Hepatocytes
Sinusoids
Portal triad = branches of hepatic a. and portal v. and bile duct
While looking at a liver slide you note the following things:
_____ ____ delineated on all sides by CT
_____ ______ = brown staining stick-like structures located in between hepatocytes
_____ ____ including portal vein branches, hepatic a. branches, and bile ductules
Hepatic lobule
Bile canaliculi
Portal triad
There are 3 ways to reference the functional organization of the liver:
______ = based on structural units of the liver
_____ = based on bile drainage pathway from adjacent lobules toward the same bile duct
______ = based on [O2] gradient along sinusoids of adjacent lobules
Hepatic lobule
Portal lobule
Liver acinus
Describe the hepatic lobule functional organization of the liver
Hexagonal in shape and centered on central venule
Portal triads are positioned at angles of hexagon
[this is classic organization]
Describe portal lobule functional organization of the liver
Portal triad is the central axis, draining bile from the surrounding hepatic parenchyma
Describe the liver acinus functional organization of the liver
Boundaries are determined by a terminal branch of the hepatic a.
Flow of arterial blood creates gradient of O2/nutrients
Establishes zones 1, 2, and 3; cells within each zone have different metabolic functions