MA - Sirotkin - Exocrine Glands - 2/13 Flashcards
What are the three major mechanisms of secretion? Provide a specific example of a gland for each type
1) Holocrine: lysis of cells filled with secretory product Example: sebaceous glands of skin
2) Apocrine: shedding of apical cell segment filled with secretory product
Example: mammary glands
3) Merocrine (called eccrine in sweat glands): exocytosis of proteins or glycoproteins
Examples: sweat glands, salivary glands, exocrine pancreas.
What are the differences between simple and compound glands?
Simple glands – single unbranched duct. Secretory portion can be branched or unbranched. Examples: sweat glands and sebaceous glands
Compound glands – multiple branched ducts. Secretory portion can be acinar, tubular, or tubuloacinar. Examples: salivary glands and exocrine pancreas
What is the composition of the sebum?
triglycerides, cholesterol, squalene, wax esters
*Clinical correlation: origin of acne.
List cell types found in the sweat glands
Pale (clear) cells
Dark cells
Myoepithelial cells
What is the function of myoepithelial cells? Where are these cells located?
- Located between basal lamina and secretory or duct cells
- Triangular or elongated nucleus
- Possess long contractile actomyosin-rich processes
- Contraction helps expel secretory product
- Present in sweat, salivary, and mammary glands
What are the three types of acini found in the salivary glands? How do their secretions differ?
Types: mucous, serous or mixed
Serous cells: secrete proteins including sIgA and bicarbonate
Mucous cells: secrete mucin (glycoproteins rich in complex carbohydrates)
What is the serous demilune? Are the serous demilunes present in the living tissue?
These are mixed acini that are fixation artifacts
What is the function of basal striations? In which glands and in what part of a gland are the basal striations found?
Basal membrane infoldings that house mitochondria found in the intralobular ducts of salivary glands
How can you differentiate the pancreas from the parotid gland on the histological preparations?
Islets of Langerhans are unique to pancreas
Adipocytes are present in parotid gland
What is the content of zymogenic granules?
Digestive proenzymes: lipases, nucleases, amylases
Which cells are responsible for producing bicarbonate in the pancreas?
● Intercalated ducts –> protrude into acini as centroacinar cells
● Intralobular ducts –> lack striations (secrete bicarbonate-rich fluid)
● Interlobular ducts –> low columnar epithelium
What are the distinguishing features of each of the three salivary glands?
Parotid gland: all serous; note adipocytes
Submandibular gland: mostly serous
Sublingual gland: mostly mucous
